Adding upstream version 0.0~git20250520.a1d9079+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>
2025-05-24 19:46:29 +02:00 · 2025-05-24 19:46:29 +02:00 · 20149b7f3a
commit 20149b7f3a
parent 590ac7ff5f
456 changed files with 70406 additions and 0 deletions
--- a/example/basic/main.go
+++ b/example/basic/main.go
@ -0,0 +1,178 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || linux || windows
+
+// An app that draws a green triangle on a red background.
+//
+// In order to build this program as an Android APK, using the gomobile tool.
+//
+// See http://godoc.org/golang.org/x/mobile/cmd/gomobile to install gomobile.
+//
+// Get the basic example and use gomobile to build or install it on your device.
+//
+//	$ go get -d golang.org/x/mobile/example/basic
+//	$ gomobile build golang.org/x/mobile/example/basic # will build an APK
+//
+//	# plug your Android device to your computer or start an Android emulator.
+//	# if you have adb installed on your machine, use gomobile install to
+//	# build and deploy the APK to an Android target.
+//	$ gomobile install golang.org/x/mobile/example/basic
+//
+// Switch to your device or emulator to start the Basic application from
+// the launcher.
+// You can also run the application on your desktop by running the command
+// below. (Note: It currently doesn't work on Windows.)
+//
+//	$ go install golang.org/x/mobile/example/basic && basic
+package main
+
+import (
+	"encoding/binary"
+	"log"
+
+	"golang.org/x/mobile/app"
+	"golang.org/x/mobile/event/lifecycle"
+	"golang.org/x/mobile/event/paint"
+	"golang.org/x/mobile/event/size"
+	"golang.org/x/mobile/event/touch"
+	"golang.org/x/mobile/exp/app/debug"
+	"golang.org/x/mobile/exp/f32"
+	"golang.org/x/mobile/exp/gl/glutil"
+	"golang.org/x/mobile/gl"
+)
+
+var (
+	images   *glutil.Images
+	fps      *debug.FPS
+	program  gl.Program
+	position gl.Attrib
+	offset   gl.Uniform
+	color    gl.Uniform
+	buf      gl.Buffer
+
+	green  float32
+	touchX float32
+	touchY float32
+)
+
+func main() {
+	app.Main(func(a app.App) {
+		var glctx gl.Context
+		var sz size.Event
+		for e := range a.Events() {
+			switch e := a.Filter(e).(type) {
+			case lifecycle.Event:
+				switch e.Crosses(lifecycle.StageVisible) {
+				case lifecycle.CrossOn:
+					glctx, _ = e.DrawContext.(gl.Context)
+					onStart(glctx)
+					a.Send(paint.Event{})
+				case lifecycle.CrossOff:
+					onStop(glctx)
+					glctx = nil
+				}
+			case size.Event:
+				sz = e
+				touchX = float32(sz.WidthPx / 2)
+				touchY = float32(sz.HeightPx / 2)
+			case paint.Event:
+				if glctx == nil || e.External {
+					// As we are actively painting as fast as
+					// we can (usually 60 FPS), skip any paint
+					// events sent by the system.
+					continue
+				}
+
+				onPaint(glctx, sz)
+				a.Publish()
+				// Drive the animation by preparing to paint the next frame
+				// after this one is shown.
+				a.Send(paint.Event{})
+			case touch.Event:
+				touchX = e.X
+				touchY = e.Y
+			}
+		}
+	})
+}
+
+func onStart(glctx gl.Context) {
+	var err error
+	program, err = glutil.CreateProgram(glctx, vertexShader, fragmentShader)
+	if err != nil {
+		log.Printf("error creating GL program: %v", err)
+		return
+	}
+
+	buf = glctx.CreateBuffer()
+	glctx.BindBuffer(gl.ARRAY_BUFFER, buf)
+	glctx.BufferData(gl.ARRAY_BUFFER, triangleData, gl.STATIC_DRAW)
+
+	position = glctx.GetAttribLocation(program, "position")
+	color = glctx.GetUniformLocation(program, "color")
+	offset = glctx.GetUniformLocation(program, "offset")
+
+	images = glutil.NewImages(glctx)
+	fps = debug.NewFPS(images)
+}
+
+func onStop(glctx gl.Context) {
+	glctx.DeleteProgram(program)
+	glctx.DeleteBuffer(buf)
+	fps.Release()
+	images.Release()
+}
+
+func onPaint(glctx gl.Context, sz size.Event) {
+	glctx.ClearColor(1, 0, 0, 1)
+	glctx.Clear(gl.COLOR_BUFFER_BIT)
+
+	glctx.UseProgram(program)
+
+	green += 0.01
+	if green > 1 {
+		green = 0
+	}
+	glctx.Uniform4f(color, 0, green, 0, 1)
+
+	glctx.Uniform2f(offset, touchX/float32(sz.WidthPx), touchY/float32(sz.HeightPx))
+
+	glctx.BindBuffer(gl.ARRAY_BUFFER, buf)
+	glctx.EnableVertexAttribArray(position)
+	glctx.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
+	glctx.DrawArrays(gl.TRIANGLES, 0, vertexCount)
+	glctx.DisableVertexAttribArray(position)
+
+	fps.Draw(sz)
+}
+
+var triangleData = f32.Bytes(binary.LittleEndian,
+	0.0, 0.4, 0.0, // top left
+	0.0, 0.0, 0.0, // bottom left
+	0.4, 0.0, 0.0, // bottom right
+)
+
+const (
+	coordsPerVertex = 3
+	vertexCount     = 3
+)
+
+const vertexShader = `#version 100
+uniform vec2 offset;
+
+attribute vec4 position;
+void main() {
+	// offset comes in with x/y values between 0 and 1.
+	// position bounds are -1 to 1.
+	vec4 offset4 = vec4(2.0*offset.x-1.0, 1.0-2.0*offset.y, 0, 0);
+	gl_Position = position + offset4;
+}`
+
+const fragmentShader = `#version 100
+precision mediump float;
+uniform vec4 color;
+void main() {
+	gl_FragColor = color;
+}`
--- a/example/basic/main_x.go
+++ b/example/basic/main_x.go
@ -0,0 +1,10 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !darwin && !linux && !windows
+
+package main
+
+func main() {
+}
--- a/example/bind/android/README
+++ b/example/bind/android/README
@ -0,0 +1,11 @@
+Go bind android app example
+
+Run
+
+$ gomobile bind -o app/hello.aar golang.org/x/mobile/example/bind/hello
+
+and import this project in Android Studio. If you prefer the command
+line, use gradle to build directly.
+
+Note that you need to run gomobile bind again every time you make a
+change to Go code.
--- a/example/bind/android/app/build.gradle
+++ b/example/bind/android/app/build.gradle
@ -0,0 +1,34 @@
+/*
+ * Copyright 2015 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+apply plugin: 'com.android.application'
+
+repositories {
+    flatDir {
+        dirs '.'
+    }
+}
+
+android {
+    compileSdkVersion 27
+
+    defaultConfig {
+        applicationId "org.golang.example.android"
+        minSdkVersion 15
+        targetSdkVersion 27
+        versionCode 1
+        versionName "1.0"
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+        }
+    }
+}
+
+dependencies {
+    implementation 'com.android.support:appcompat-v7:22.1.1'
+    implementation (name:'hello', ext:'aar')
+}
--- a/example/bind/android/app/src/main/AndroidManifest.xml
+++ b/example/bind/android/app/src/main/AndroidManifest.xml
@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2015 The Go Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style
+     license that can be found in the LICENSE file.  -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="org.golang.example.bind" >
+
+    <application
+        android:allowBackup="true"
+        android:label="GoBindExample">
+        <activity
+            android:name=".MainActivity"
+            android:label="GoBindExample" >
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>
--- a/example/bind/android/app/src/main/java/org/golang/example/bind/MainActivity.java
+++ b/example/bind/android/app/src/main/java/org/golang/example/bind/MainActivity.java
@ -0,0 +1,29 @@
+/*
+ * Copyright 2015 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+package org.golang.example.bind;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.widget.TextView;
+
+import hello.Hello;
+
+public class MainActivity extends Activity {
+
+    private TextView mTextView;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        mTextView = (TextView) findViewById(R.id.mytextview);
+
+        // Call Go function.
+        String greetings = Hello.greetings("Android and Gopher");
+        mTextView.setText(greetings);
+    }
+}
--- a/example/bind/android/app/src/main/res/layout/activity_main.xml
+++ b/example/bind/android/app/src/main/res/layout/activity_main.xml
@ -0,0 +1,17 @@
+<!-- Copyright 2015 The Go Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style
+     license that can be found in the LICENSE file. -->
+
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
+    android:paddingRight="@dimen/activity_horizontal_margin"
+    android:paddingTop="@dimen/activity_vertical_margin"
+    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:id="@+id/mytextview" />
+
+</RelativeLayout>
--- a/example/bind/android/app/src/main/res/values/dimens.xml
+++ b/example/bind/android/app/src/main/res/values/dimens.xml
@ -0,0 +1,8 @@
+<!-- Copyright 2015 The Go Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style
+     license that can be found in the LICENSE file.  -->
+<resources>
+    <!-- Default screen margins, per the Android Design guidelines. -->
+    <dimen name="activity_horizontal_margin">16dp</dimen>
+    <dimen name="activity_vertical_margin">16dp</dimen>
+</resources>
--- a/example/bind/android/build.gradle
+++ b/example/bind/android/build.gradle
@ -0,0 +1,21 @@
+/* Copyright 2015 The Go Authors. All rights reserved.
+ *  Use of this source code is governed by a BSD-style
+ *  license that can be found in the LICENSE file.
+ */
+
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.1.0'
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
--- a/example/bind/android/settings.gradle
+++ b/example/bind/android/settings.gradle
@ -0,0 +1,5 @@
+/* Copyright 2015 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+include ':app'
--- a/example/bind/hello/hello.go
+++ b/example/bind/hello/hello.go
@ -0,0 +1,12 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package hello is a trivial package for gomobile bind example.
+package hello
+
+import "fmt"
+
+func Greetings(name string) string {
+	return fmt.Sprintf("Hello, %s!", name)
+}
--- a/example/flappy/assets/README
+++ b/example/flappy/assets/README
@ -0,0 +1,2 @@
+The sprites were created by Renee French and are distributed
+under the Creative Commons Attributions 3.0 license.
--- a/example/flappy/assets/sprite.png
+++ b/example/flappy/assets/sprite.png
--- a/example/flappy/game.go
+++ b/example/flappy/game.go
@ -0,0 +1,356 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || linux
+
+package main
+
+import (
+	"image"
+	"log"
+	"math"
+	"math/rand"
+
+	_ "image/png"
+
+	"golang.org/x/mobile/asset"
+	"golang.org/x/mobile/exp/f32"
+	"golang.org/x/mobile/exp/sprite"
+	"golang.org/x/mobile/exp/sprite/clock"
+)
+
+const (
+	tileWidth, tileHeight = 16, 16 // width and height of each tile
+	tilesX, tilesY        = 16, 16 // number of horizontal tiles
+
+	gopherTile = 1 // which tile the gopher is standing on (0-indexed)
+
+	initScrollV = 1     // initial scroll velocity
+	scrollA     = 0.001 // scroll acceleration
+	gravity     = 0.1   // gravity
+	jumpV       = -5    // jump velocity
+	flapV       = -1.5  // flap velocity
+
+	deadScrollA         = -0.01 // scroll deceleration after the gopher dies
+	deadTimeBeforeReset = 240   // how long to wait before restarting the game
+
+	groundChangeProb = 5 // 1/probability of ground height change
+	groundWobbleProb = 3 // 1/probability of minor ground height change
+	groundMin        = tileHeight * (tilesY - 2*tilesY/5)
+	groundMax        = tileHeight * tilesY
+	initGroundY      = tileHeight * (tilesY - 1)
+
+	climbGrace = tileHeight / 3 // gopher won't die if it hits a cliff this high
+)
+
+type Game struct {
+	gopher struct {
+		y        float32    // y-offset
+		v        float32    // velocity
+		atRest   bool       // is the gopher on the ground?
+		flapped  bool       // has the gopher flapped since it became airborne?
+		dead     bool       // is the gopher dead?
+		deadTime clock.Time // when the gopher died
+	}
+	scroll struct {
+		x float32 // x-offset
+		v float32 // velocity
+	}
+	groundY   [tilesX + 3]float32 // ground y-offsets
+	groundTex [tilesX + 3]int     // ground texture
+	lastCalc  clock.Time          // when we last calculated a frame
+}
+
+func NewGame() *Game {
+	var g Game
+	g.reset()
+	return &g
+}
+
+func (g *Game) reset() {
+	g.gopher.y = 0
+	g.gopher.v = 0
+	g.scroll.x = 0
+	g.scroll.v = initScrollV
+	for i := range g.groundY {
+		g.groundY[i] = initGroundY
+		g.groundTex[i] = randomGroundTexture()
+	}
+	g.gopher.atRest = false
+	g.gopher.flapped = false
+	g.gopher.dead = false
+	g.gopher.deadTime = 0
+}
+
+func (g *Game) Scene(eng sprite.Engine) *sprite.Node {
+	texs := loadTextures(eng)
+
+	scene := &sprite.Node{}
+	eng.Register(scene)
+	eng.SetTransform(scene, f32.Affine{
+		{1, 0, 0},
+		{0, 1, 0},
+	})
+
+	newNode := func(fn arrangerFunc) {
+		n := &sprite.Node{Arranger: arrangerFunc(fn)}
+		eng.Register(n)
+		scene.AppendChild(n)
+	}
+
+	// The ground.
+	for i := range g.groundY {
+		i := i
+		// The top of the ground.
+		newNode(func(eng sprite.Engine, n *sprite.Node, t clock.Time) {
+			eng.SetSubTex(n, texs[g.groundTex[i]])
+			eng.SetTransform(n, f32.Affine{
+				{tileWidth, 0, float32(i)*tileWidth - g.scroll.x},
+				{0, tileHeight, g.groundY[i]},
+			})
+		})
+		// The earth beneath.
+		newNode(func(eng sprite.Engine, n *sprite.Node, t clock.Time) {
+			eng.SetSubTex(n, texs[texEarth])
+			eng.SetTransform(n, f32.Affine{
+				{tileWidth, 0, float32(i)*tileWidth - g.scroll.x},
+				{0, tileHeight * tilesY, g.groundY[i] + tileHeight},
+			})
+		})
+	}
+
+	// The gopher.
+	newNode(func(eng sprite.Engine, n *sprite.Node, t clock.Time) {
+		a := f32.Affine{
+			{tileWidth * 2, 0, tileWidth*(gopherTile-1) + tileWidth/8},
+			{0, tileHeight * 2, g.gopher.y - tileHeight + tileHeight/4},
+		}
+		var x int
+		switch {
+		case g.gopher.dead:
+			x = frame(t, 16, texGopherDead1, texGopherDead2)
+			animateDeadGopher(&a, t-g.gopher.deadTime)
+		case g.gopher.v < 0:
+			x = frame(t, 4, texGopherFlap1, texGopherFlap2)
+		case g.gopher.atRest:
+			x = frame(t, 4, texGopherRun1, texGopherRun2)
+		default:
+			x = frame(t, 8, texGopherRun1, texGopherRun2)
+		}
+		eng.SetSubTex(n, texs[x])
+		eng.SetTransform(n, a)
+	})
+
+	return scene
+}
+
+// frame returns the frame for the given time t
+// when each frame is displayed for duration d.
+func frame(t, d clock.Time, frames ...int) int {
+	total := int(d) * len(frames)
+	return frames[(int(t)%total)/int(d)]
+}
+
+func animateDeadGopher(a *f32.Affine, t clock.Time) {
+	dt := float32(t)
+	a.Scale(a, 1+dt/20, 1+dt/20)
+	a.Translate(a, 0.5, 0.5)
+	a.Rotate(a, dt/math.Pi/-8)
+	a.Translate(a, -0.5, -0.5)
+}
+
+type arrangerFunc func(e sprite.Engine, n *sprite.Node, t clock.Time)
+
+func (a arrangerFunc) Arrange(e sprite.Engine, n *sprite.Node, t clock.Time) { a(e, n, t) }
+
+const (
+	texGopherRun1 = iota
+	texGopherRun2
+	texGopherFlap1
+	texGopherFlap2
+	texGopherDead1
+	texGopherDead2
+	texGround1
+	texGround2
+	texGround3
+	texGround4
+	texEarth
+)
+
+func randomGroundTexture() int {
+	return texGround1 + rand.Intn(4)
+}
+
+func loadTextures(eng sprite.Engine) []sprite.SubTex {
+	a, err := asset.Open("sprite.png")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer a.Close()
+
+	m, _, err := image.Decode(a)
+	if err != nil {
+		log.Fatal(err)
+	}
+	t, err := eng.LoadTexture(m)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	const n = 128
+	// The +1's and -1's in the rectangles below are to prevent colors from
+	// adjacent textures leaking into a given texture.
+	// See: http://stackoverflow.com/questions/19611745/opengl-black-lines-in-between-tiles
+	return []sprite.SubTex{
+		texGopherRun1:  sprite.SubTex{t, image.Rect(n*0+1, 0, n*1-1, n)},
+		texGopherRun2:  sprite.SubTex{t, image.Rect(n*1+1, 0, n*2-1, n)},
+		texGopherFlap1: sprite.SubTex{t, image.Rect(n*2+1, 0, n*3-1, n)},
+		texGopherFlap2: sprite.SubTex{t, image.Rect(n*3+1, 0, n*4-1, n)},
+		texGopherDead1: sprite.SubTex{t, image.Rect(n*4+1, 0, n*5-1, n)},
+		texGopherDead2: sprite.SubTex{t, image.Rect(n*5+1, 0, n*6-1, n)},
+		texGround1:     sprite.SubTex{t, image.Rect(n*6+1, 0, n*7-1, n)},
+		texGround2:     sprite.SubTex{t, image.Rect(n*7+1, 0, n*8-1, n)},
+		texGround3:     sprite.SubTex{t, image.Rect(n*8+1, 0, n*9-1, n)},
+		texGround4:     sprite.SubTex{t, image.Rect(n*9+1, 0, n*10-1, n)},
+		texEarth:       sprite.SubTex{t, image.Rect(n*10+1, 0, n*11-1, n)},
+	}
+}
+
+func (g *Game) Press(down bool) {
+	if g.gopher.dead {
+		// Player can't control a dead gopher.
+		return
+	}
+
+	if down {
+		switch {
+		case g.gopher.atRest:
+			// Gopher may jump from the ground.
+			g.gopher.v = jumpV
+		case !g.gopher.flapped:
+			// Gopher may flap once in mid-air.
+			g.gopher.flapped = true
+			g.gopher.v = flapV
+		}
+	} else {
+		// Stop gopher rising on button release.
+		if g.gopher.v < 0 {
+			g.gopher.v = 0
+		}
+	}
+}
+
+func (g *Game) Update(now clock.Time) {
+	if g.gopher.dead && now-g.gopher.deadTime > deadTimeBeforeReset {
+		// Restart if the gopher has been dead for a while.
+		g.reset()
+	}
+
+	// Compute game states up to now.
+	for ; g.lastCalc < now; g.lastCalc++ {
+		g.calcFrame()
+	}
+}
+
+func (g *Game) calcFrame() {
+	g.calcScroll()
+	g.calcGopher()
+}
+
+func (g *Game) calcScroll() {
+	// Compute velocity.
+	if g.gopher.dead {
+		// Decrease scroll speed when the gopher dies.
+		g.scroll.v += deadScrollA
+		if g.scroll.v < 0 {
+			g.scroll.v = 0
+		}
+	} else {
+		// Increase scroll speed.
+		g.scroll.v += scrollA
+	}
+
+	// Compute offset.
+	g.scroll.x += g.scroll.v
+
+	// Create new ground tiles if we need to.
+	for g.scroll.x > tileWidth {
+		g.newGroundTile()
+
+		// Check whether the gopher has crashed.
+		// Do this for each new ground tile so that when the scroll
+		// velocity is >tileWidth/frame it can't pass through the ground.
+		if !g.gopher.dead && g.gopherCrashed() {
+			g.killGopher()
+		}
+	}
+}
+
+func (g *Game) calcGopher() {
+	// Compute velocity.
+	g.gopher.v += gravity
+
+	// Compute offset.
+	g.gopher.y += g.gopher.v
+
+	g.clampToGround()
+}
+
+func (g *Game) newGroundTile() {
+	// Compute next ground y-offset.
+	next := g.nextGroundY()
+	nextTex := randomGroundTexture()
+
+	// Shift ground tiles to the left.
+	g.scroll.x -= tileWidth
+	copy(g.groundY[:], g.groundY[1:])
+	copy(g.groundTex[:], g.groundTex[1:])
+	last := len(g.groundY) - 1
+	g.groundY[last] = next
+	g.groundTex[last] = nextTex
+}
+
+func (g *Game) nextGroundY() float32 {
+	prev := g.groundY[len(g.groundY)-1]
+	if change := rand.Intn(groundChangeProb) == 0; change {
+		return (groundMax-groundMin)*rand.Float32() + groundMin
+	}
+	if wobble := rand.Intn(groundWobbleProb) == 0; wobble {
+		return prev + (rand.Float32()-0.5)*climbGrace
+	}
+	return prev
+}
+
+func (g *Game) gopherCrashed() bool {
+	return g.gopher.y+tileHeight-climbGrace > g.groundY[gopherTile+1]
+}
+
+func (g *Game) killGopher() {
+	g.gopher.dead = true
+	g.gopher.deadTime = g.lastCalc
+	g.gopher.v = jumpV * 1.5 // Bounce off screen.
+}
+
+func (g *Game) clampToGround() {
+	if g.gopher.dead {
+		// Allow the gopher to fall through ground when dead.
+		return
+	}
+
+	// Compute the minimum offset of the ground beneath the gopher.
+	minY := g.groundY[gopherTile]
+	if y := g.groundY[gopherTile+1]; y < minY {
+		minY = y
+	}
+
+	// Prevent the gopher from falling through the ground.
+	maxGopherY := minY - tileHeight
+	g.gopher.atRest = false
+	if g.gopher.y >= maxGopherY {
+		g.gopher.v = 0
+		g.gopher.y = maxGopherY
+		g.gopher.atRest = true
+		g.gopher.flapped = false
+	}
+}
--- a/example/flappy/main.go
+++ b/example/flappy/main.go
@ -0,0 +1,98 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || linux
+
+// Flappy Gopher is a simple one-button game that uses the
+// mobile framework and the experimental sprite engine.
+package main
+
+import (
+	"math/rand"
+	"time"
+
+	"golang.org/x/mobile/app"
+	"golang.org/x/mobile/event/key"
+	"golang.org/x/mobile/event/lifecycle"
+	"golang.org/x/mobile/event/paint"
+	"golang.org/x/mobile/event/size"
+	"golang.org/x/mobile/event/touch"
+	"golang.org/x/mobile/exp/gl/glutil"
+	"golang.org/x/mobile/exp/sprite"
+	"golang.org/x/mobile/exp/sprite/clock"
+	"golang.org/x/mobile/exp/sprite/glsprite"
+	"golang.org/x/mobile/gl"
+)
+
+func main() {
+	rand.Seed(time.Now().UnixNano())
+
+	app.Main(func(a app.App) {
+		var glctx gl.Context
+		var sz size.Event
+		for e := range a.Events() {
+			switch e := a.Filter(e).(type) {
+			case lifecycle.Event:
+				switch e.Crosses(lifecycle.StageVisible) {
+				case lifecycle.CrossOn:
+					glctx, _ = e.DrawContext.(gl.Context)
+					onStart(glctx)
+					a.Send(paint.Event{})
+				case lifecycle.CrossOff:
+					onStop()
+					glctx = nil
+				}
+			case size.Event:
+				sz = e
+			case paint.Event:
+				if glctx == nil || e.External {
+					continue
+				}
+				onPaint(glctx, sz)
+				a.Publish()
+				a.Send(paint.Event{}) // keep animating
+			case touch.Event:
+				if down := e.Type == touch.TypeBegin; down || e.Type == touch.TypeEnd {
+					game.Press(down)
+				}
+			case key.Event:
+				if e.Code != key.CodeSpacebar {
+					break
+				}
+				if down := e.Direction == key.DirPress; down || e.Direction == key.DirRelease {
+					game.Press(down)
+				}
+			}
+		}
+	})
+}
+
+var (
+	startTime = time.Now()
+	images    *glutil.Images
+	eng       sprite.Engine
+	scene     *sprite.Node
+	game      *Game
+)
+
+func onStart(glctx gl.Context) {
+	images = glutil.NewImages(glctx)
+	eng = glsprite.Engine(images)
+	game = NewGame()
+	scene = game.Scene(eng)
+}
+
+func onStop() {
+	eng.Release()
+	images.Release()
+	game = nil
+}
+
+func onPaint(glctx gl.Context, sz size.Event) {
+	glctx.ClearColor(1, 1, 1, 1)
+	glctx.Clear(gl.COLOR_BUFFER_BIT)
+	now := clock.Time(time.Since(startTime) * 60 / time.Second)
+	game.Update(now)
+	eng.Render(scene, now, sz)
+}
--- a/example/flappy/main_x.go
+++ b/example/flappy/main_x.go
@ -0,0 +1,10 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !darwin && !linux
+
+package main
+
+func main() {
+}
--- a/example/ivy/android/README.md
+++ b/example/ivy/android/README.md
@ -0,0 +1,38 @@
+## Ivy Big Number Calculator (Android)
+
+[Ivy (robpike.io/ivy)](https://robpike.io/ivy) is an interpreter for an APL-like language written in Go.
+This repository hosts a minimal Android project used for its [Android version](https://play.google.com/store/apps/details?id=org.golang.ivy&hl=en_US&gl=US).
+
+### How to build
+
+Requirements
+  - Go 1.17 or newer
+  - Android SDK
+  - Android NDK
+  - `golang.org/x/mobile/cmd/gomobile`
+
+The `gomobile` command respects the `ANDROID_HOME` and `ANDROID_NDK_HOME` environment variables.  If `gomobile` can't find your SDK and NDK, you can set these environment variables to specify their locations:
+```
+export ANDROID_HOME=/path/to/sdk-directory
+export ANDROID_NDK_HOME=/path/to/ndk-directory
+```
+
+From this directory, run:
+
+```sh
+  go install golang.org/x/mobile/cmd/gomobile@latest
+  go install golang.org/x/mobile/cmd/gobind@latest
+
+  # Make sure `gomobile` and `gobind` is in your `PATH`.
+  gomobile bind -o app/ivy.aar robpike.io/ivy/mobile
+```
+
+Open this directory from Android Studio, and build.
+
+`robpike.io/ivy` and `golang.org/x/mobile` are required dependencies of this main module. In order to update them:
+
+```
+  go get -d golang.org/x/mobile@latest
+  go get -d robpike.io/ivy/mobile
+  go mod tidy
+```
--- a/example/ivy/android/app/build.gradle
+++ b/example/ivy/android/app/build.gradle
@ -0,0 +1,25 @@
+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 30
+    defaultConfig {
+        applicationId 'org.golang.ivy'
+        minSdkVersion 15
+        targetSdkVersion 30
+        versionCode 4
+        versionName '1.4.0'
+    }
+    buildTypes {
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+    productFlavors {
+    }
+}
+
+dependencies {
+    implementation 'androidx.appcompat:appcompat:1.0.0'
+    implementation files('ivy.aar')
+}
--- a/example/ivy/android/app/proguard-rules.pro
+++ b/example/ivy/android/app/proguard-rules.pro
@ -0,0 +1,17 @@
+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in /Users/hakim/Library/Android/sdk/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
--- a/example/ivy/android/app/src/androidTest/java/org/golang/ivy/ApplicationTest.java
+++ b/example/ivy/android/app/src/androidTest/java/org/golang/ivy/ApplicationTest.java
@ -0,0 +1,13 @@
+package org.golang.ivy;
+
+import android.app.Application;
+import android.test.ApplicationTestCase;
+
+/**
+ * <a href="http://d.android.com/tools/testing/testing_android.html">Testing Fundamentals</a>
+ */
+public class ApplicationTest extends ApplicationTestCase<Application> {
+    public ApplicationTest() {
+        super(Application.class);
+    }
+}
--- a/example/ivy/android/app/src/main/AndroidManifest.xml
+++ b/example/ivy/android/app/src/main/AndroidManifest.xml
@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    package="org.golang.ivy"
+    android:installLocation="auto">
+
+    <!-- undo gradle's auto addition of unrequested permissions
+    http://stackoverflow.com/questions/27410382/unrequested-permissions-not-declared-in-androidmanifest-crashlytics-maybe -->
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" tools:node="remove" />
+    <uses-permission android:name="android.permission.READ_PHONE_STATE" tools:node="remove" />
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" tools:node="remove" />
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:logo="@mipmap/ic_launcher"
+        android:theme="@style/IvyAppTheme"
+        android:windowSoftInputMode="adjustResize|stateAlwaysVisible"
+        android:fullBackupContent="true">
+        <activity
+            android:name=".MainActivity"
+            android:icon="@mipmap/ic_launcher"
+            android:label="@string/app_name"
+            android:logo="@mipmap/ic_launcher"
+            android:windowSoftInputMode="adjustResize|stateUnchanged|stateAlwaysVisible"
+            android:configChanges="orientation|screenSize"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <activity
+            android:name=".Help"
+            android:label="@string/title_activity_help"
+            android:parentActivityName=".MainActivity">
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value="org.golang.ivy.MainActivity" />
+        </activity>
+        <activity
+            android:name=".AboutIvy"
+            android:label="@string/title_activity_about"
+            android:parentActivityName=".MainActivity">
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value="org.golang.ivy.MainActivity" />
+        </activity>
+    </application>
+
+</manifest>
--- a/example/ivy/android/app/src/main/assets/aboutivy.html
+++ b/example/ivy/android/app/src/main/assets/aboutivy.html
@ -0,0 +1,21 @@
+<!--
+Copyright 2015 The Go Authors. All rights reserved.
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file.
+-->
+<html>
+<body>
+    <center>
+    <h2>Ivy</h2><p>
+
+    Based on <a href='https://robpike.io/ivy'>robpike.io/ivy</a>
+    <p>
+    Copyright 2015 The <a href='https://golang.org/LICENSE'>Go Authors</a>.
+    <br>
+    The Ivy mascot is designed by
+    <a href='https://reneefrench.blogspot.com/'>Renee French</a>
+    and licensed under the
+    <a href='https://creativecommons.org/licenses/by/3.0/us/'>Creative Commons Attribution 3.0 license</a>.
+    </center>
+</body>
+</html>
--- a/example/ivy/android/app/src/main/assets/demo.ivy
+++ b/example/ivy/android/app/src/main/assets/demo.ivy
@ -0,0 +1,263 @@
+# This is a demo of ivy. Type a newline to advance to each new step. Type one now.
+# At any time, type the word "quit" or EOF to end the demo and return to ivy.
+# Each step in the demo is one line of input followed by some output from ivy. Type a newline now to see.
+2+2
+# The first line you see above (2+2) is input; the next (4) is output from a running ivy.
+# Comments start with # and produce no output.
+# Whenever you like, you can type an expression yourself. Try typing 2*3 now, followed by two newlines:
+# Keep typing newlines; the ivy demo is about to start.
+# Arithmetic has the obvious operations: + - * etc. ** is exponentiation. mod is modulo.
+23
+23 + 45
+23 * 45
+23 - 45
+7 ** 3
+7 mod 3
+# Operator precedence is unusual.
+# Unary operators operate on everything to the right.
+# Binary operators operate on the item immediately to the left, and everything to the right.
+2*3+4     # Parsed as 2*(3+4), not the usual (2*3)+4.
+2**2+3    # 2**5, not (2**2) + 3
+(2**2)+3  # Use parentheses if you need to group differently.
+# Ivy can do rational arithmetic, so 1/3 is really 1/3, not 0.333....
+1/3
+1/3 + 4/5
+1/3 ** 2  # We'll see non-integral exponents later.
+# Even when a number is input in floating notation, it is still an exact rational number inside.
+1.2
+# In fact, ivy is a "bignum" calculator that can handle huge numbers and rationals made of huge numbers.
+1e10       # Still an integer.
+1e100      # Still an integer.
+1e10/3     # Not an integer, but an exact rational.
+3/1e10     # Not an integer, but an exact rational.
+2**64      # They can get big.
+2**640     # They can get really big.
+# They can get really really big. Type a newline to see 2**6400 scroll by.
+2**6400
+# Ivy also has characters, which represent a Unicode code point.
+'x'
+char 0x61     # char is an operator: character with given value.
+char 0x1f4a9
+code '💩'      # char's inverse, the value of given character, here printed in decimal.
+# Everything in ivy can be placed into a vector.
+# Vectors are written and displayed with spaces between the elements.
+1 2 3
+1 4/3 5/3 (2+1/3)
+# Note that without the parens this becomes (1 4/3 5/3 2)+1/3
+1 4/3 5/3 2+1/3
+# Vectors of characters print without quotes or spaces.
+'h' 'e' 'l' 'l' 'o'
+# This is a nicer way to write 'h' 'e' 'l' 'l' 'o'. It means the same.
+'hello'
+# Arithmetic works elementwise on vectors.
+1 2 3 + 4 5 6
+# Arithmetic between scalar and vector also works, either way.
+23 + 1 2 3
+1 2 3 + 23   # Note the grouping: vector is a single value.
+# More fun with scalar and vector.
+1 << 1 2 3 4 5
+(1 << 1 2 3 4 5) == (2 ** 1 2 3 4 5)  # Note: true is 1, false is 0.
+# iota is an "index generator": It counts from 1.
+iota 10
+2 ** iota 5
+(1 << iota 100) == 2 ** iota 100
+2 ** -1 + iota 32 # Again, see how the precedence rules work.
+# The take operator removes n items from the beginning of the vector.
+3 take iota 10
+-3 take iota 10     # Negative n takes from the end.
+# Drop is the other half: it drops n from the vector.
+3 drop iota 10
+-3 drop iota 10     # Negative n drops from the end.
+6 drop 'hello world'
+# Reduction
+iota 15
+# Add them up:
+1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15
+# Automate this by reducing + over the vector, like this:
+/iota 15
+# We can reduce using any binary operator. This is factorial:
+1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10
+*/iota 10
+*/iota 100
+# Type this: */iota 10000
+# That printed using floating-point notation for manageability but it is still an integer inside.
+# max and min are binary operators that do the obvious. (Use semicolons to separate expressions.)
+3 max 7; 'is max and'; 3 min 7; 'is min'
+# Like all binary arithmetic operators, max applies elementwise.
+2 3 4 max 4 3 2
+# Reduce using max to find maximum element in vector.
+max/2 34 42 233 2 2 521 14 1 4 1 55 133
+# Ivy allows multidimensional arrays. The binary shape operator, rho, builds them.
+# Dimension (which may be a vector) on the left, data on the right.
+5 rho 1
+5 5 rho 1
+5 5 rho 25
+5 5 rho iota 25
+3 5 5 rho iota 125
+# Unary rho tells us the shape of an item.
+x = 3 5 rho iota 15; x
+rho x
+x = 3 5 5 rho iota 75; x
+rho x
+# Arithmetic on matrices works as you would expect by now.
+x/2
+x**2
+x**3
+x**10
+# Inner product is written with a . between the operators.
+# This gives dot product: multiply corresponding elements and add the result.
+1 2 3 4 +.* 2 3 4 5
+# Any operator works. How many items are the same?
+(1 2 3) +.== (1 3 3)
+# How many differ?
+(1 2 3) +.!= (1 3 3)
+# Outer product generates a matrix of all combinations applying the binary operator.
+(iota 5) o.* -1 + iota 5
+# That's a letter 'o', dot, star.
+# Any operator works; here is how to make an identity matrix.
+x = iota 5; x o.== x
+# Assignment is an operator, so you can save an intermediate expression.
+x o.== x = iota 5
+# Random numbers: Use a unary ? to roll an n-sided die from 1 to n.
+?100
+?100
+?20 rho 6  # 20 rolls of a 6-sided die.
+x = ?20 rho 6 # Remember one set of rolls.
+x
+# Indexing is easy.
+x[1]
+x[1 19 3]  # You can index with a vector.
+# The up and down operators generate index vectors that would sort the input.
+up x
+x[up x]
+x[down x]
+'hello world'[up 'hello world']
+'hello world'[down 'hello world']
+# More rolls of a die.
+?10 rho 6
+# Remember a set of rolls.
+x = ?10 rho 6; x
+# The outer product of == and the integers puts 1 in each row where that value appeared.
+# Compare the last row of the next result to the 6s in x.
+(iota 6) o.== x
+# Count the number of times each value appears by reducing the matrix horizontally.
+/(iota 6) o.== x
+# Do it for a much larger set of rolls: is the die fair?
+/(iota 6) o.== ?60000 rho 6
+# Remember that ivy is a big number calculator.
+*/iota 100
+2**64
+2**iota 64
+-1+2**63
+# Settings are made and queried with a leading right paren. )help helps with settings and other commands.
+)help
+# Use )base to switch input and output to base 16.
+)base 16
+)base   # The input and output for settings is always base 10.
+# _ is a variable that holds the most recently evaluated expression. It remembers our 63-bit number.
+_
+1<<iota 10   # 16 powers of two, base 16.
+(2**40)-1    # The largest 64-bit number base 16.
+)obase 10    # Output base 10, input base still 16.
+)base
+# The largest 63-bit number base 10.
+-1+2**40            # The largest 64-bit number base 10.
+-1+2**3F            # The largest 63-bit number base 10.
+# Go back to base 10 input and output.
+)base 10
+# Rationals can be very big too.
+(2**1e3)/(3**1e2)
+# Such output can be unwieldy. Change the output format using a Printf string.
+)format '%.12g'
+_
+# We need more precision.
+)format "%.100g"    # Double quotes work too; there's no difference.
+_
+)format '%#x'
+_
+)format '%.12g'     # A nice format, easily available by running ivy -g.
+_
+(3 4 rho iota 12)/4
+# Irrational functions cannot be represented precisely by rational numbers.
+# Ivy stores irrational results in high-precision (default 256-bit) floating point numbers.
+sqrt 2
+# pi and e are built-in, high-precision constants.
+pi
+e
+)format "%.100g"
+pi
+)format '%.12g'
+pi
+# Exponentials and logarithms.
+2**1/2  # Note: Non-integral exponent generates irrational result.
+e**1e6
+log e**1e6
+log e**1e8
+log 1e1000000    # Yes, that is 10 to the millionth power.
+# Transcendentals. (The low bit isn't always right...)
+sin pi/2
+cos .25*pi * -1 + iota 9
+log iota 6
+# Successive approximations to e. (We force the calculation to use float using the "float" unary operator. Why?)
+(float 1+10**-iota 9) ** 10**iota 9
+# Default precision is 256 bits of mantissa. We can go up to 10000.
+)prec 3350         # Units are bits, not digits. 2 log 10 == 3.321. Add a few more bits for floating point errors.
+e
+)format '%.1000g'  # Units are digits. (Sorry for the inconsistency.)
+e
+pi
+sqrt 2
+e**1e6
+log e**1e6
+(2**1e3)/(3**1e2)
+# User-defined operators are declared as unary or binary (or both). This one computes the (unary) average.
+op avg x = (+/x)/rho x
+avg iota 100
+# Here is a binary operator.
+op n largest x = n take x[down x]
+3 largest ? 100 rho 1000
+4 largest 'hello world'
+# Population count. Use encode to turn the value into a string of bits. Use log to decide how many.
+op a base b = ((ceil b log a) rho b) encode a
+7 base 2
+op popcount n = +/n base 2
+popcount 7
+popcount 1e6
+popcount 1e100
+# Here is one to sum the digits. The unary operator text turns its argument into text, like sprintf.
+op sumdigits x = t = text x; +/(code (t in '0123456789') sel t) - code '0'
+# Break it down:  The sel operator selects from the right based on the non-zero elements in the left.
+# The in operator generates a selector by choosing only the bytes that are ASCII digits.
+sumdigits 99
+sumdigits iota 10
+sumdigits '23 skidoo'  # Note: It counts only the digits.
+# The binary text operator takes a format string (% optional) on the left and formats the value.
+'%x' text 1234
+# We can use this for another version of popcount: %b is binary.
+op popcount n = +/'1' == '%b' text n
+popcount 7
+popcount 1e6
+popcount 1e100
+# A classic (expensive!) algorithm to count primes.
+op primes N = (not T in T o.* T) sel T = 1 drop iota N
+# The assignment to T gives 2..N. We use outer product to build an array of all products.
+# Then we find all elements of T that appear in the product matrix, invert that, and select from the original.
+primes 100
+# A final trick.
+# The binary ? operator "deals": x?y selects at random x distinct integers from 1..y inclusive.
+5?10
+# We can use this to shuffle a deck of cards. The suits are ♠♡♣♢, the values
+# A234567890JQK (using 0 for 10, for simplicity).
+# Create the deck using outer product with the ravel operator:
+"A234567890JQK" o., "♠♡♣♢"
+# To shuffle it, ravel into into a vector and index that by 1 through 52, shuffled.
+(, "A234567890JQK" o., "♠♡♣♢")[52?52]
+# There is no looping construct in ivy, but there is a conditional evaluator.
+# Within a user-defined operator, one can write a condition expression
+# using a binary operator, ":". If the left-hand operand is true (integer non-zero),
+# the user-defined operator will return the right-hand operand as its
+# result; otherwise execution continues.
+op a gcd b = a == b: a; a > b: b gcd a-b; a gcd b-a
+1562 gcd !11
+# That's it! Have fun.
+# For more information visit https://pkg.go.dev/robpike.io/ivy
--- a/example/ivy/android/app/src/main/assets/tape.html
+++ b/example/ivy/android/app/src/main/assets/tape.html
@ -0,0 +1,61 @@
+<!--
+Copyright 2015 The Go Authors. All rights reserved.
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file.
+-->
+<html>
+<head>
+    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no" charset="UTF-8">
+    <style>
+        body {
+            font-family: sans-serif;
+        }
+        div {
+            padding: 1;
+            white-space: pre-wrap;
+            font-family: "Roboto Mono", monospace;
+        }
+        .comment {
+            color: grey;
+        }
+        .expr {
+            font-weight: bold;
+        }
+        .flow-hide {
+            text-overflow: ellipsis;
+            word-break: break-all;
+            white-space: nowrap;
+            overflow: hidden;
+        }
+        .flow-show {
+            word-break: break-all;
+        }
+    </style>
+
+    <script>
+
+function flowClick(el) {
+    el.classList.toggle("flow-hide");
+    el.classList.toggle("flow-show");
+}
+
+function appendDiv(txt, tag) {
+    var el = document.createElement("div");
+    el.innerHTML = txt;
+    if (tag == "comment") {
+        el.classList.add("comment");
+    } else if (tag == "expr") {
+        el.classList.add("expr");
+    } else {
+        el.classList.add("flow-show");
+        el.onclick = function() {
+                flowClick(el);
+        };
+    }
+    document.body.appendChild(el);
+}
+
+</script>
+<body>
+</body>
+</html>
--- a/example/ivy/android/app/src/main/ic_launcher-web.png
+++ b/example/ivy/android/app/src/main/ic_launcher-web.png
--- a/example/ivy/android/app/src/main/java/org/golang/ivy/AboutIvy.java
+++ b/example/ivy/android/app/src/main/java/org/golang/ivy/AboutIvy.java
@ -0,0 +1,56 @@
+/*
+ * Copyright 2015 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+package org.golang.ivy;
+
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.ViewGroup;
+import android.webkit.WebView;
+import android.webkit.WebViewClient;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+/*
+ * Handles About menu item.
+ */
+public class AboutIvy extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_about);
+
+        LayoutInflater inflater = getLayoutInflater();
+        View layout = inflater.inflate(R.layout.activity_about,
+                (ViewGroup) findViewById(R.id.about_layout));
+
+        WebView webView = (WebView) layout.findViewById(R.id.about_ivy);
+        webView.setWebViewClient(new WebViewClient(){
+            public boolean shouldOverrideUrlLoading(WebView view, String url) {
+                if (url != null && (url.startsWith("https://") || url.startsWith("http://"))) {
+                    view.getContext().startActivity(
+                            new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
+                    return true;
+                } else {
+                    return false;
+                }
+            }
+        });
+        webView.getSettings().setDefaultTextEncodingName("utf-8");
+        webView.loadUrl("file:///android_asset/aboutivy.html");
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        onBackPressed();  // back to parent.
+        return true;
+    }
+}
--- a/example/ivy/android/app/src/main/java/org/golang/ivy/Help.java
+++ b/example/ivy/android/app/src/main/java/org/golang/ivy/Help.java
@ -0,0 +1,54 @@
+/**
+ * Copyright 2015 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+package org.golang.ivy;
+
+
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Bundle;
+import android.view.MenuItem;
+import android.webkit.WebView;
+import android.webkit.WebViewClient;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import mobile.Mobile;
+
+/*
+ * Displays the help message for Ivy.
+ */
+public class Help extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_help);
+        WebView webView = (WebView) findViewById(R.id.help_webview);
+        webView.setWebViewClient(new WebViewClient() {
+            public boolean shouldOverrideUrlLoading(WebView view, String url) {
+                // we are not a browser; redirect the request to proper apps.
+                if (url != null) {
+                    view.getContext().startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
+                }
+                return true;
+            }
+        });
+        webView.getSettings().setDefaultTextEncodingName("utf-8");
+        // mobile.Mobile was generated using gomobile bind robpike.io/ivy/mobile.
+        String helpMsg = Mobile.help();
+
+        // loadData has a rendering bug: https://code.google.com/p/android/issues/detail?id=6965
+        webView.loadDataWithBaseURL("http://pkg.go.dev/robpike.io/ivy", helpMsg, "text/html", "UTF-8", null);
+        webView.setBackgroundColor(getResources().getColor(R.color.body));
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        onBackPressed();  // back to parent.
+        return true;
+    }
+}
--- a/example/ivy/android/app/src/main/java/org/golang/ivy/MainActivity.java
+++ b/example/ivy/android/app/src/main/java/org/golang/ivy/MainActivity.java
@ -0,0 +1,356 @@
+/*
+ * Copyright 2015 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+package org.golang.ivy;
+
+import android.content.Intent;
+import android.content.pm.ApplicationInfo;
+import android.net.Uri;
+import android.os.AsyncTask;
+import android.os.Build;
+import android.os.Bundle;
+import android.text.TextUtils;
+import android.util.Log;
+import android.util.Pair;
+import android.view.KeyEvent;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
+import android.view.View;
+import android.webkit.WebView;
+import android.webkit.WebViewClient;
+import android.widget.EditText;
+import android.widget.ImageButton;
+import android.widget.ScrollView;
+import android.widget.Toast;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+// This is in ivy.aar.
+import mobile.Mobile;
+
+/*
+ * Main activity that consists of an edit view to accept the expression
+ * and a web view to display output of the expression.
+ */
+public class MainActivity extends AppCompatActivity {
+    final String DEMO_SCRIPT = "demo.ivy";  // in assets directory.
+    final String DEBUG_TAG = "Ivy";
+
+    private WebView mWebView;
+    private EditText mEditText;
+    private ScrollView mScroller;
+
+    private BufferedReader mDemo;
+    private ImageButton mOKButton;  // enabled only in demo mode.
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+
+        mScroller = (ScrollView) findViewById(R.id.scroller);
+        mWebView = (WebView) findViewById(R.id.webView);
+        mEditText = (EditText) findViewById(R.id.editText);
+        mOKButton = (ImageButton) findViewById(R.id.imageButton);
+        mOKButton.setVisibility(View.GONE);
+
+        if (savedInstanceState != null) {
+            mWebView.restoreState(savedInstanceState);
+        } else {
+            clear();
+        }
+        configureWebView(mWebView);
+
+        mEditText.requestFocus();
+        mEditText.setOnKeyListener(new View.OnKeyListener() {
+            public boolean onKey(View v, int keyCode, KeyEvent event) {
+                if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) {
+                    callIvy();
+                    return true;
+                }
+                return false;
+            }
+        });
+
+        mOKButton.setOnClickListener(new View.OnClickListener() {
+            public void onClick(View v) {
+                callIvy();
+            }
+        });
+
+        /* For webview debugging - visit chrome://inspect/#devices */
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            if (0 != (getApplicationInfo().flags & ApplicationInfo.FLAG_DEBUGGABLE))
+            { WebView.setWebContentsDebuggingEnabled(true); }
+        }
+    }
+
+    @Override
+    protected void onSaveInstanceState(Bundle outState) {
+        mWebView.saveState(outState);
+        super.onSaveInstanceState(outState);
+    }
+
+    public void onRestoreInstanceState(Bundle savedInstanceState) {
+        super.onRestoreInstanceState(savedInstanceState);
+        mWebView.restoreState(savedInstanceState);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        MenuInflater inflater = getMenuInflater();
+        inflater.inflate(R.menu.menu_main, menu);
+        return true;
+    }
+
+    private long mLastPress = 0;
+    @Override
+    public void onBackPressed() {
+        // TODO: store and restore the state across app restarts.
+        long currentTime = System.currentTimeMillis();
+        if(currentTime - mLastPress > 6000){
+            Toast.makeText(getBaseContext(), "Press back again to exit.\nAll app state will be lost upon exit.", Toast.LENGTH_LONG).show();
+            mLastPress = currentTime;
+        }else{
+            super.onBackPressed();
+        }
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        int id = item.getItemId();
+        switch (id) {
+            case R.id.action_about:
+                startActivity(new Intent(this, AboutIvy.class));
+                return true;
+            case R.id.action_help:
+                startActivity(new Intent(this, Help.class));
+                return true;
+            case R.id.action_clear:
+                clear();
+                return true;
+            case R.id.action_demo:
+                loadDemo();
+                return true;
+            default:
+                return super.onOptionsItemSelected(item);
+        }
+    }
+
+    private void clear() {
+        // As described in https://code.google.com/p/android/issues/detail?id=18726
+        // clearing the contents of the webview doesn't shrink the webview size in some
+        // old versions of Android. (e.g. Moto X running 4.4.4). I tried various techniques
+        // suggested in the Internet, but nothing worked except creating a new webview.
+        WebView newView = new WebView(this);
+        newView.setLayoutParams(mWebView.getLayoutParams());
+        newView.setId(R.id.webView);
+
+        configureWebView(newView);
+
+        mScroller.removeView(mWebView);
+        mWebView.destroy();
+
+        mWebView = newView;
+        mWebView.loadUrl("file:///android_asset/tape.html");
+        mWebView.setBackgroundColor(getResources().getColor(R.color.body));
+        mScroller.addView(mWebView);
+
+        mEditText.setText("");
+        Mobile.reset();
+        unloadDemo();
+    }
+
+    void configureWebView(WebView webView) {
+        // We enable javascript, but disallow any url loading.
+        webView.getSettings().setJavaScriptEnabled(true);
+        webView.setWebViewClient(new WebViewClient() {
+            // Disallow arbitrary contents loaded into our own webview.
+            public boolean shouldOverrideUrlLoading(WebView view, String url) {
+                view.getContext().startActivity(
+                        new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
+                return true;
+            }
+        });
+        webView.setFocusable(false);
+        webView.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
+            @Override
+            public void onLayoutChange(View v, int left, int top, int right, int bottom,
+                                       int oldLeft, int oldTop, int oldRight, int oldBottom) {
+                // It's possible that the layout is not complete.
+                // In that case we will get all zero values for the positions. Ignore this case.
+                if (left == 0 && top == 0 && right == 0 && bottom == 0) {
+                    return;
+                }
+                scrollToBottom();
+            }
+        });
+    }
+
+    private String escapeHtmlTags(final String s) {
+        // Leaves entities (&-prefixed) alone unlike TextUtils.htmlEncode
+        // (https://github.com/aosp-mirror/platform_frameworks_base/blob/d59921149bb5948ffbcb9a9e832e9ac1538e05a0/core/java/android/text/TextUtils.java#L1361).
+        // Ivy mobile.Eval result may include encoding starting with &.
+
+        StringBuilder sb = new StringBuilder();
+        char c;
+        for (int i = 0; i < s.length(); i++) {
+            c = s.charAt(i);
+            switch (c) {
+                case '<':
+                    sb.append("&lt;"); //$NON-NLS-1$
+                    break;
+                case '>':
+                    sb.append("&gt;"); //$NON-NLS-1$
+                    break;
+                case '"':
+                    sb.append("&quot;"); //$NON-NLS-1$
+                    break;
+                case '\'':
+                    //http://www.w3.org/TR/xhtml1
+                    // The named character reference &apos; (the apostrophe, U+0027) was introduced in
+                    // XML 1.0 but does not appear in HTML. Authors should therefore use &#39; instead
+                    // of &apos; to work as expected in HTML 4 user agents.
+                    sb.append("&#39;"); //$NON-NLS-1$
+                    break;
+                default:
+                    sb.append(c);
+            }
+        }
+        return sb.toString();
+    }
+
+    private void appendShowText(final String s, final String tag) {
+        mWebView.loadUrl("javascript:appendDiv('" + TextUtils.htmlEncode(s).replaceAll("(\r\n|\n)", "<br />") + "', '" + tag + "')");
+        mWebView.setBackgroundColor(getResources().getColor(R.color.body));
+    }
+
+    private void appendShowPreformattedText(final String s, final String tag) {
+        mWebView.loadUrl("javascript:appendDiv('" + escapeHtmlTags(s).replaceAll("\r?\n", "<br/>") + "', '" + tag + "')");
+        mWebView.setBackgroundColor(getResources().getColor(R.color.body));
+    }
+
+    private void callIvy() {
+        String s = mEditText.getText().toString().trim();
+        if (s != null && !s.isEmpty()) {
+            appendShowText(s, "expr");
+        }
+        if (mDemo != null && s.trim().equals("quit")) {
+            unloadDemo();
+            s = " ";  // this will clear the text box.
+        }
+        new IvyCallTask().execute(s);  // where call to Ivy backend occurs.
+    }
+
+    private synchronized void loadDemo() {
+        try {
+            if (mDemo == null) {
+                mDemo = new BufferedReader(new InputStreamReader(getAssets().open(DEMO_SCRIPT), "UTF-8"));
+            }
+            mOKButton.setVisibility(View.VISIBLE);
+            new IvyCallTask().execute("");
+        } catch (IOException e) {
+            Toast.makeText(this, "Failed to load Demo script.\nContact the app author.", Toast.LENGTH_SHORT);
+        }
+    }
+
+    private synchronized void unloadDemo() {
+        if (mDemo == null) { return; }
+        try {
+            mDemo.close();
+        } catch (IOException e) {
+            Log.d(DEBUG_TAG, e.toString());
+        }
+        mDemo = null;
+        mOKButton.setVisibility(View.GONE);
+    }
+
+    private synchronized String readDemo() {
+        if (mDemo == null) { return null; }
+        try {
+            return mDemo.readLine();
+        } catch (IOException e) {
+            unloadDemo();
+        }
+        return null;
+    }
+
+    private void scrollToBottom() {
+        mScroller.post(new Runnable() {
+            public void run() {
+                mScroller.smoothScrollTo(0, mWebView.getBottom());
+            }
+        });
+    }
+
+    // AsyncTask that evaluates the expression (string), and returns the strings
+    // to display in the web view and the edit view respectively.
+    private class IvyCallTask extends AsyncTask<String, Void, Pair<String, String> > {
+        private String ivyEval(final String expr) {
+            try {
+                // mobile.Mobile was generated using
+                // gomobile bind -javapkg=org.golang.ivy robpike.io/ivy/mobile
+                return Mobile.eval(expr);  // Gobind-generated method.
+            } catch (Exception e) {
+                return "error: "+e.getMessage();
+            }
+        }
+
+        // doInBackground checks the demo script (if the passed-in param is empty),
+        // or returns the ivy evaluation result.
+        @Override
+        protected Pair<String, String> doInBackground(String ...param) {
+            final String expr = param[0];
+            // TODO: cancel, timeout
+            if (expr == null || expr.isEmpty()) {
+                return checkDemo();
+            }
+            return Pair.create(ivyEval(expr), "");
+        }
+
+        // checkDemo reads the demo script and returns the comment, and the next expression.
+        protected Pair<String, String> checkDemo() {
+            String showText = null;
+            while (true) {
+                String s = readDemo();
+                if (s == null) {
+                    break;
+                }
+                if (s.startsWith("# ")) {
+                    return Pair.create(s, null);
+                }
+                return Pair.create(null, s);
+            }
+            return null;
+        }
+
+        @Override
+        protected void onPostExecute(final Pair<String, String> result) {
+            if (result == null || (result.first == null && result.second == null)) {
+                return;
+            }
+            runOnUiThread(new Runnable() {
+                @Override
+                public void run() {
+                    String showText = result.first;
+                    if (showText != null) {
+                        final String tag = (showText.startsWith("#")) ? "comment" : "result";
+                        appendShowPreformattedText(showText, tag);
+                    }
+                    String editText = result.second;
+                    if (editText != null) {
+                        mEditText.setText(editText);
+                    }
+                }
+            });
+        }
+    }
+}
--- a/example/ivy/android/app/src/main/res/drawable-hdpi/actionbar_solid.png
+++ b/example/ivy/android/app/src/main/res/drawable-hdpi/actionbar_solid.png
--- a/example/ivy/android/app/src/main/res/drawable-hdpi/ic_done_white_24dp.png
+++ b/example/ivy/android/app/src/main/res/drawable-hdpi/ic_done_white_24dp.png
--- a/example/ivy/android/app/src/main/res/drawable-mdpi/actionbar_solid.png
+++ b/example/ivy/android/app/src/main/res/drawable-mdpi/actionbar_solid.png
--- a/example/ivy/android/app/src/main/res/drawable-mdpi/ic_done_white_24dp.png
+++ b/example/ivy/android/app/src/main/res/drawable-mdpi/ic_done_white_24dp.png
--- a/example/ivy/android/app/src/main/res/drawable-xhdpi/actionbar_solid.png
+++ b/example/ivy/android/app/src/main/res/drawable-xhdpi/actionbar_solid.png
--- a/example/ivy/android/app/src/main/res/drawable-xhdpi/ic_done_white_24dp.png
+++ b/example/ivy/android/app/src/main/res/drawable-xhdpi/ic_done_white_24dp.png
--- a/example/ivy/android/app/src/main/res/drawable-xxhdpi/actionbar_solid.png
+++ b/example/ivy/android/app/src/main/res/drawable-xxhdpi/actionbar_solid.png
--- a/example/ivy/android/app/src/main/res/drawable-xxhdpi/ic_done_white_24dp.png
+++ b/example/ivy/android/app/src/main/res/drawable-xxhdpi/ic_done_white_24dp.png
--- a/example/ivy/android/app/src/main/res/drawable/circle_shape.xml
+++ b/example/ivy/android/app/src/main/res/drawable/circle_shape.xml
@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+<item android:state_pressed="false">
+    <shape android:shape="oval">
+        <solid android:color="@color/blue"/>
+    </shape>
+</item>
+<item android:state_pressed="true">
+    <shape android:shape="oval">
+        <solid android:color="@color/button_material_dark"/>
+    </shape>
+</item>
+</selector>
--- a/example/ivy/android/app/src/main/res/drawable/ivyabout.png
+++ b/example/ivy/android/app/src/main/res/drawable/ivyabout.png
--- a/example/ivy/android/app/src/main/res/layout/activity_about.xml
+++ b/example/ivy/android/app/src/main/res/layout/activity_about.xml
@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/about_layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="#EEFFFFFF"
+    android:gravity="center"
+    android:orientation="vertical"
+    android:padding="10dp"
+    android:weightSum="1"
+    tools:context="org.golang.ivy.About">
+
+    <ImageView
+        android:id="@+id/ivysketch"
+        android:src="@drawable/ivyabout"
+        android:layout_gravity="center_horizontal"
+        android:layout_width="256dp"
+        android:layout_height="256dp"
+        android:contentDescription="@string/ivysketch_desc" />
+
+    <WebView
+        android:id="@+id/about_ivy"
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent"
+        android:text="@string/app_name"
+        android:textSize="@dimen/abc_text_size_headline_material" />
+
+</LinearLayout>
--- a/example/ivy/android/app/src/main/res/layout/activity_help.xml
+++ b/example/ivy/android/app/src/main/res/layout/activity_help.xml
@ -0,0 +1,14 @@
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="fill_parent"
+    android:layout_height="match_parent"
+    tools:context="org.golang.ivy.Help"
+    android:background="@color/body">
+
+    <WebView
+        android:id="@+id/help_webview"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:background="@color/body" />
+
+</RelativeLayout>
--- a/example/ivy/android/app/src/main/res/layout/activity_main.xml
+++ b/example/ivy/android/app/src/main/res/layout/activity_main.xml
@ -0,0 +1,69 @@
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".MainActivity"
+    android:id="@+id/layout"
+    android:background="@color/body">
+
+    <ScrollView
+        android:id="@+id/scroller"
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent"
+        android:scrollbars="vertical"
+        android:fillViewport="false"
+        android:layout_alignParentTop="true"
+        android:layout_alignParentLeft="true"
+        android:layout_alignParentStart="true"
+        android:layout_above="@+id/layout_bottom"
+        android:padding="@dimen/abc_control_padding_material">
+
+        <WebView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:id="@+id/webView"
+            android:gravity="left|bottom"
+            android:textIsSelectable="true"
+            android:clickable="false"
+            android:background="@color/body" />
+
+    </ScrollView>
+
+    <LinearLayout
+        android:orientation="horizontal"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_centerHorizontal="true"
+        android:id="@+id/layout_bottom"
+        android:layout_alignParentRight="true"
+        android:layout_alignParentEnd="true"
+        android:layout_alignParentLeft="true"
+        android:layout_alignParentStart="true"
+        android:layout_alignParentBottom="true">
+
+        <EditText
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:id="@+id/editText"
+            android:gravity="top|left|start"
+            android:textStyle="normal"
+            android:inputType="textVisiblePassword"
+            android:hint="@string/editTextHelp"/>
+
+        <ImageButton
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:id="@+id/imageButton"
+            android:background="@drawable/circle_shape"
+            android:src="@drawable/ic_done_white_24dp"
+            android:contentDescription="@string/ok"
+            android:onClick="onClick"
+            android:clickable="true"
+            android:padding="@dimen/abc_control_padding_material"
+            android:layout_margin="@dimen/abc_control_padding_material" />
+
+    </LinearLayout>
+
+</RelativeLayout>
--- a/example/ivy/android/app/src/main/res/menu/menu_about.xml
+++ b/example/ivy/android/app/src/main/res/menu/menu_about.xml
@ -0,0 +1,10 @@
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    tools:context="org.golang.ivy.About">
+    <item
+        android:id="@+id/action_settings"
+        android:title="@string/action_settings"
+        android:orderInCategory="100"
+        app:showAsAction="never" />
+</menu>
--- a/example/ivy/android/app/src/main/res/menu/menu_main.xml
+++ b/example/ivy/android/app/src/main/res/menu/menu_main.xml
@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:ivyapp="http://schemas.android.com/apk/res-auto">
+
+
+    <item
+        android:id="@+id/action_clear"
+        android:title="@string/action_clear"
+        ivyapp:showAsAction="always" />
+    <item
+        android:id="@+id/action_demo"
+        android:title="@string/action_demo"
+        ivyapp:showAsAction="collapseActionView" />
+    <item
+        android:id="@+id/action_help"
+        android:title="@string/action_help"
+        ivyapp:showAsAction="collapseActionView" />
+    <item
+        android:id="@+id/action_about"
+        android:title="@string/action_about"
+        ivyapp:showAsAction="collapseActionView" />
+
+</menu>
--- a/example/ivy/android/app/src/main/res/mipmap-hdpi/ic_launcher.png
+++ b/example/ivy/android/app/src/main/res/mipmap-hdpi/ic_launcher.png
--- a/example/ivy/android/app/src/main/res/mipmap-mdpi/ic_launcher.png
+++ b/example/ivy/android/app/src/main/res/mipmap-mdpi/ic_launcher.png
--- a/example/ivy/android/app/src/main/res/mipmap-xhdpi/ic_launcher.png
+++ b/example/ivy/android/app/src/main/res/mipmap-xhdpi/ic_launcher.png
--- a/example/ivy/android/app/src/main/res/mipmap-xxhdpi/ic_launcher.png
+++ b/example/ivy/android/app/src/main/res/mipmap-xxhdpi/ic_launcher.png
--- a/example/ivy/android/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
+++ b/example/ivy/android/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
--- a/example/ivy/android/app/src/main/res/values-w820dp/dimens.xml
+++ b/example/ivy/android/app/src/main/res/values-w820dp/dimens.xml
@ -0,0 +1,6 @@
+<resources>
+    <!-- Example customization of dimensions originally defined in res/values/dimens.xml
+         (such as screen margins) for screens with more than 820dp of available width. This
+         would include 7" and 10" devices in landscape (~960dp and ~1280dp respectively). -->
+    <dimen name="activity_horizontal_margin">64dp</dimen>
+</resources>
--- a/example/ivy/android/app/src/main/res/values-w820dp/strings.xml
+++ b/example/ivy/android/app/src/main/res/values-w820dp/strings.xml
@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="ok">OK</string>
+</resources>
--- a/example/ivy/android/app/src/main/res/values/colors.xml
+++ b/example/ivy/android/app/src/main/res/values/colors.xml
@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<resources>
+
+    <color name="body">#ffffeb</color>
+    <color name="sky">#e2f6ff</color>
+    <color name="blue">#1997d4</color>
+    <color name="white">#f9f9f9</color>
+    <color name="black">#000000</color>
+
+</resources>
--- a/example/ivy/android/app/src/main/res/values/dimens.xml
+++ b/example/ivy/android/app/src/main/res/values/dimens.xml
@ -0,0 +1,5 @@
+<resources>
+    <!-- Default screen margins, per the Android Design guidelines. -->
+    <dimen name="activity_horizontal_margin">16dp</dimen>
+    <dimen name="activity_vertical_margin">16dp</dimen>
+</resources>
--- a/example/ivy/android/app/src/main/res/values/strings.xml
+++ b/example/ivy/android/app/src/main/res/values/strings.xml
@ -0,0 +1,51 @@
+<resources>
+    <string name="app_name">Ivy</string>
+
+    <string name="hello_world">Hello world!</string>
+    <string name="action_settings">Settings</string>
+    <string name="action_help">Help</string>
+    <string name="action_about">About</string>
+    <string name="action_clear">Clear</string>
+    <string name="action_demo">Demo</string>
+
+
+    <string name="about_details">by Go Authors</string>
+    <string name="title_activity_about">About Ivy</string>
+    <string name="title_activity_help">Help</string>
+    <string name="ivy_sketch">ivy_sketch</string>
+    <string name="editTextHelp">type an expression</string>
+    <string name="ivysketch_desc">ivy sketch</string>
+    <string name="ok">OK</string>
+
+    <string-array name="expression_array">
+        <item>ceil</item>
+        <item>floor</item>
+        <item>rho</item>
+        <item>abs</item>
+        <item>iota</item>
+        <item>sgn</item>
+        <item>rev</item>
+        <item>flip</item>
+        <item>up</item>
+        <item>down</item>
+        <item>div</item>
+        <item>idiv</item>
+        <item>max</item>
+        <item>min</item>
+        <item>rho</item>
+        <item>take</item>
+        <item>drop</item>
+        <item>mod</item>
+        <item>imod</item>
+        <item>or</item>
+        <item>and</item>
+        <item>nor</item>
+        <item>nand</item>
+        <item>xor</item>
+        <item>def</item>
+        <item>) format</item>
+        <item>) op</item>
+        <item>) base</item>
+        <item>) origin</item>
+    </string-array>
+</resources>
--- a/example/ivy/android/app/src/main/res/values/styles.xml
+++ b/example/ivy/android/app/src/main/res/values/styles.xml
@ -0,0 +1,16 @@
+<resources>
+
+    <style name="IvyAppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+        <item name="colorControlActivated">@color/sky</item>
+        <item name="colorPrimary">@color/blue</item>
+        <item name="colorPrimaryDark">@color/blue</item>
+        <item name="actionBarStyle">@style/MyActionBarLogo</item>
+    </style>
+
+
+    <style name="MyActionBarLogo" parent="Theme.AppCompat.Light.DarkActionBar">
+        <item name="background">@color/blue</item>
+        <item name="logo">@mipmap/ic_launcher</item>
+        <item name="displayOptions">useLogo|showHome</item>
+    </style>
+</resources>
--- a/example/ivy/android/build.gradle
+++ b/example/ivy/android/build.gradle
@ -0,0 +1,18 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+buildscript {
+    repositories {
+        mavenCentral()
+        google()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:7.0.3'
+    }
+}
+
+allprojects {
+    repositories {
+        mavenCentral()
+        google()
+    }
+}
--- a/example/ivy/android/settings.gradle
+++ b/example/ivy/android/settings.gradle
@ -0,0 +1 @@
+include ':app'
--- a/example/ivy/doc.go
+++ b/example/ivy/doc.go
@ -0,0 +1,7 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This is an empty package.
+// We have this package to convince this is buildable and go mod tidy can work.
+package dummy
--- a/example/ivy/go.mod
+++ b/example/ivy/go.mod
@ -0,0 +1,15 @@
+module golang.org/x/mobile/example/ivy
+
+go 1.23.0
+
+require (
+	golang.org/x/mobile v0.0.0-20210924032853-1c027f395ef7
+	robpike.io/ivy v0.2.7
+)
+
+require (
+	golang.org/x/mod v0.4.2 // indirect
+	golang.org/x/sys v0.0.0-20210510120138-977fb7262007 // indirect
+	golang.org/x/tools v0.1.2 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+)
--- a/example/ivy/go.sum
+++ b/example/ivy/go.sum
@ -0,0 +1,40 @@
+github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
+golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
+golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
+golang.org/x/mobile v0.0.0-20210924032853-1c027f395ef7 h1:CyFUjc175y/mbMjxe+WdqI72jguLyjQChKCDe9mfTvg=
+golang.org/x/mobile v0.0.0-20210924032853-1c027f395ef7/go.mod h1:c4YKU3ZylDmvbw+H/PSvm42vhdWbuxCzbonauEAP9B8=
+golang.org/x/mod v0.1.0/go.mod h1:0QHyrYULN0/3qlju5TqG8bIK38QM8yzMo5ekMj3DlcY=
+golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20190312151545-0bb0c0a6e846/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.2 h1:kRBLX7v7Af8W7Gdbbc908OJcdgtK8bOz9Uaj8/F1ACA=
+golang.org/x/tools v0.1.2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+robpike.io/ivy v0.2.7 h1:XVYgWSm7THVm1bk1jfRBB9xhso459T22gbpotHbhk7M=
+robpike.io/ivy v0.2.7/go.mod h1:6B/DGaft5rvYiF7MgCTiZAAvH5W7vtu0eS2BW77updo=
--- a/example/ivy/ios/README.md
+++ b/example/ivy/ios/README.md
@ -0,0 +1,27 @@
+# Ivy iOS App source
+
+This directory contains the source code to the Ivy iOS app.
+
+To build, first create the Mobile.xcframework out of the Go
+implementation of Ivy. Run:
+
+```
+go install golang.org/x/mobile/cmd/gomobile@latest
+go install golang.org/x/mobile/cmd/gobind@latest
+```
+
+to install `gomobile` and `gobind`. Then:
+
+```
+mkdir work; cd work
+go mod init work
+go get -d golang.org/x/mobile/bind@latest
+go get -d robpike.io/ivy/mobile
+gomobile bind -target=ios,iossimulator,maccatalyst,macos robpike.io/ivy/mobile robpike.io/ivy/demo
+```
+
+Place the Mobile.xcframework directory in this directory, and
+then open ivy.xcodeproj in Xcode.
+
+You have to specify Development Team for code signing certificate in:
+Project Settings -> Targets -> Signing & Capabilities -> Signing -> Team.
--- a/example/ivy/ios/ivy.xcodeproj/project.pbxproj
+++ b/example/ivy/ios/ivy.xcodeproj/project.pbxproj
@ -0,0 +1,391 @@
+// !$*UTF8*$!
+{
+	archiveVersion = 1;
+	classes = {
+	};
+	objectVersion = 52;
+	objects = {
+
+/* Begin PBXBuildFile section */
+		7DC2F7EA26DFD9870026EBED /* WebKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 7DC2F7E826DFCF750026EBED /* WebKit.framework */; };
+		7DC2F7ED26DFD9890026EBED /* Mobile.xcframework in Frameworks */ = {isa = PBXBuildFile; fileRef = B4C2833A1B98889100878964 /* Mobile.xcframework */; };
+		B461D25D1B31B27700EC4870 /* tape.html in Resources */ = {isa = PBXBuildFile; fileRef = B461D25C1B31B27700EC4870 /* tape.html */; };
+		B48878331B2E714100C7CC3C /* AppDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = B488780C1B2D1C3F00C7CC3C /* AppDelegate.m */; };
+		B48878341B2E714100C7CC3C /* IvyController.m in Sources */ = {isa = PBXBuildFile; fileRef = B488780F1B2D1C3F00C7CC3C /* IvyController.m */; };
+		B48878351B2E714100C7CC3C /* main.m in Sources */ = {isa = PBXBuildFile; fileRef = B48878091B2D1C3F00C7CC3C /* main.m */; };
+		B48878371B2E714100C7CC3C /* Suggestion.m in Sources */ = {isa = PBXBuildFile; fileRef = B48878311B2DF1B200C7CC3C /* Suggestion.m */; };
+		B48878381B2E719000C7CC3C /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = B48878111B2D1C3F00C7CC3C /* Main.storyboard */; };
+		B48878391B2E719000C7CC3C /* Images.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = B48878141B2D1C3F00C7CC3C /* Images.xcassets */; };
+		B488783D1B2F9CD500C7CC3C /* DocsController.m in Sources */ = {isa = PBXBuildFile; fileRef = B488783C1B2F9CD500C7CC3C /* DocsController.m */; };
+/* End PBXBuildFile section */
+
+/* Begin PBXFileReference section */
+		7DC2F7E826DFCF750026EBED /* WebKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = WebKit.framework; path = System/Library/Frameworks/WebKit.framework; sourceTree = SDKROOT; };
+		B461D25C1B31B27700EC4870 /* tape.html */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.html; path = tape.html; sourceTree = "<group>"; };
+		B48878041B2D1C3F00C7CC3C /* ivy.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = ivy.app; sourceTree = BUILT_PRODUCTS_DIR; };
+		B48878081B2D1C3F00C7CC3C /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
+		B48878091B2D1C3F00C7CC3C /* main.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = main.m; sourceTree = "<group>"; };
+		B488780B1B2D1C3F00C7CC3C /* AppDelegate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = AppDelegate.h; sourceTree = "<group>"; };
+		B488780C1B2D1C3F00C7CC3C /* AppDelegate.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = AppDelegate.m; sourceTree = "<group>"; };
+		B488780E1B2D1C3F00C7CC3C /* IvyController.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = IvyController.h; sourceTree = "<group>"; };
+		B488780F1B2D1C3F00C7CC3C /* IvyController.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = IvyController.m; sourceTree = "<group>"; };
+		B48878121B2D1C3F00C7CC3C /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/Main.storyboard; sourceTree = "<group>"; };
+		B48878141B2D1C3F00C7CC3C /* Images.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Images.xcassets; sourceTree = "<group>"; };
+		B48878301B2DF1B200C7CC3C /* Suggestion.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Suggestion.h; sourceTree = "<group>"; };
+		B48878311B2DF1B200C7CC3C /* Suggestion.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = Suggestion.m; sourceTree = "<group>"; };
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+		};
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+
+/* Begin PBXGroup section */
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+			);
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+		};
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+			);
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+		};
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+				B488780E1B2D1C3F00C7CC3C /* IvyController.h */,
+				B488780F1B2D1C3F00C7CC3C /* IvyController.m */,
+				B488783B1B2F9CD500C7CC3C /* DocsController.h */,
+				B488783C1B2F9CD500C7CC3C /* DocsController.m */,
+				B48878301B2DF1B200C7CC3C /* Suggestion.h */,
+				B48878311B2DF1B200C7CC3C /* Suggestion.m */,
+				B461D25C1B31B27700EC4870 /* tape.html */,
+				B48878111B2D1C3F00C7CC3C /* Main.storyboard */,
+				B48878141B2D1C3F00C7CC3C /* Images.xcassets */,
+				B48878071B2D1C3F00C7CC3C /* Supporting Files */,
+			);
+			path = ivy;
+			sourceTree = "<group>";
+		};
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+			isa = PBXGroup;
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+				B48878081B2D1C3F00C7CC3C /* Info.plist */,
+				B48878091B2D1C3F00C7CC3C /* main.m */,
+			);
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+			);
+			buildRules = (
+			);
+			dependencies = (
+			);
+			name = ivy;
+			productName = ivy;
+			productReference = B48878041B2D1C3F00C7CC3C /* ivy.app */;
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+				en,
+				Base,
+			);
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+				B48878031B2D1C3F00C7CC3C /* ivy */,
+			);
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+/* End PBXProject section */
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+/* Begin PBXResourcesBuildPhase section */
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+			isa = PBXResourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				B48878381B2E719000C7CC3C /* Main.storyboard in Resources */,
+				B48878391B2E719000C7CC3C /* Images.xcassets in Resources */,
+				B461D25D1B31B27700EC4870 /* tape.html in Resources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXResourcesBuildPhase section */
+
+/* Begin PBXSourcesBuildPhase section */
+		B48878001B2D1C3F00C7CC3C /* Sources */ = {
+			isa = PBXSourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				B48878331B2E714100C7CC3C /* AppDelegate.m in Sources */,
+				B488783D1B2F9CD500C7CC3C /* DocsController.m in Sources */,
+				B48878341B2E714100C7CC3C /* IvyController.m in Sources */,
+				B48878351B2E714100C7CC3C /* main.m in Sources */,
+				B48878371B2E714100C7CC3C /* Suggestion.m in Sources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXSourcesBuildPhase section */
+
+/* Begin PBXVariantGroup section */
+		B48878111B2D1C3F00C7CC3C /* Main.storyboard */ = {
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+			children = (
+				B48878121B2D1C3F00C7CC3C /* Base */,
+			);
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+				);
+				GCC_SYMBOLS_PRIVATE_EXTERN = NO;
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
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+				GCC_WARN_UNUSED_FUNCTION = YES;
+				GCC_WARN_UNUSED_VARIABLE = YES;
+				IPHONEOS_DEPLOYMENT_TARGET = 14.0;
+				MTL_ENABLE_DEBUG_INFO = NO;
+				SDKROOT = iphoneos;
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+				VALID_ARCHS = "arm64 x86_64 armv7";
+			};
+			name = Release;
+		};
+		B48878281B2D1C3F00C7CC3C /* Debug */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CODE_SIGN_IDENTITY = "iPhone Developer";
+				DEVELOPMENT_TEAM = "";
+				FRAMEWORK_SEARCH_PATHS = (
+					"$(inherited)",
+					"$(PROJECT_DIR)",
+				);
+				INFOPLIST_FILE = ivy/Info.plist;
+				IPHONEOS_DEPLOYMENT_TARGET = 14.0;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
+				LIBRARY_SEARCH_PATHS = (
+					"$(inherited)",
+					"$(PROJECT_DIR)",
+				);
+				ONLY_ACTIVE_ARCH = NO;
+				PRODUCT_BUNDLE_IDENTIFIER = "com.google.${PRODUCT_NAME:rfc1034identifier}";
+				PRODUCT_NAME = ivy;
+				STRIP_STYLE = debugging;
+				SUPPORTS_MACCATALYST = YES;
+				TARGETED_DEVICE_FAMILY = "1,2,6";
+				VALID_ARCHS = "arm64 x86_64 armv7";
+			};
+			name = Debug;
+		};
+		B48878291B2D1C3F00C7CC3C /* Release */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CODE_SIGN_IDENTITY = "iPhone Developer";
+				DEVELOPMENT_TEAM = "";
+				FRAMEWORK_SEARCH_PATHS = (
+					"$(inherited)",
+					"$(PROJECT_DIR)",
+				);
+				INFOPLIST_FILE = ivy/Info.plist;
+				IPHONEOS_DEPLOYMENT_TARGET = 14.0;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
+				LIBRARY_SEARCH_PATHS = (
+					"$(inherited)",
+					"$(PROJECT_DIR)",
+				);
+				ONLY_ACTIVE_ARCH = NO;
+				PRODUCT_BUNDLE_IDENTIFIER = "com.google.${PRODUCT_NAME:rfc1034identifier}";
+				PRODUCT_NAME = ivy;
+				STRIP_STYLE = debugging;
+				SUPPORTS_MACCATALYST = YES;
+				TARGETED_DEVICE_FAMILY = "1,2,6";
+				VALID_ARCHS = "arm64 x86_64 armv7";
+			};
+			name = Release;
+		};
+/* End XCBuildConfiguration section */
+
+/* Begin XCConfigurationList section */
+		B48877FF1B2D1C3F00C7CC3C /* Build configuration list for PBXProject "ivy" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				B48878251B2D1C3F00C7CC3C /* Debug */,
+				B48878261B2D1C3F00C7CC3C /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+		B48878271B2D1C3F00C7CC3C /* Build configuration list for PBXNativeTarget "ivy" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				B48878281B2D1C3F00C7CC3C /* Debug */,
+				B48878291B2D1C3F00C7CC3C /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+/* End XCConfigurationList section */
+	};
+	rootObject = B48877FC1B2D1C3F00C7CC3C /* Project object */;
+}
--- a/example/ivy/ios/ivy/AppDelegate.h
+++ b/example/ivy/ios/ivy/AppDelegate.h
@ -0,0 +1,14 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import <WebKit/WebKit.h>
+#import "IvyController.h"
+#import "Suggestion.h"
+
+@interface AppDelegate : UIResponder <UIApplicationDelegate, UITextFieldDelegate, WKUIDelegate>
+
+@property(strong, nonatomic) UIWindow *window;
+
+@end
+
--- a/example/ivy/ios/ivy/AppDelegate.m
+++ b/example/ivy/ios/ivy/AppDelegate.m
@ -0,0 +1,35 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import "AppDelegate.h"
+#import "IvyController.h"
+
+@interface AppDelegate ()
+
+@end
+
+@implementation AppDelegate
+
+- (BOOL)application:(UIApplication *)application
+    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
+  return YES;
+}
+
+- (void)applicationWillResignActive:(UIApplication *)application {
+}
+
+- (void)applicationDidEnterBackground:(UIApplication *)application {
+}
+
+- (void)applicationWillEnterForeground:(UIApplication *)application {
+}
+
+- (void)applicationDidBecomeActive:(UIApplication *)application {
+}
+
+- (void)applicationWillTerminate:(UIApplication *)application {
+}
+
+@end
+
--- a/example/ivy/ios/ivy/Base.lproj/Main.storyboard
+++ b/example/ivy/ios/ivy/Base.lproj/Main.storyboard
@ -0,0 +1,178 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="19162" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="mTw-C8-NzX">
+    <device id="retina6_1" orientation="portrait" appearance="light"/>
+    <accessibilityOverrides isEnabled="YES"/>
+    <dependencies>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="19144"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <scenes>
+        <!--Docs-->
+        <scene sceneID="qSe-m0-5Rh">
+            <objects>
+                <viewController title="Docs" id="rfr-rm-AXI" customClass="DocsController" sceneMemberID="viewController">
+                    <layoutGuides>
+                        <viewControllerLayoutGuide type="top" id="TeY-hL-zeC"/>
+                        <viewControllerLayoutGuide type="bottom" id="Yrx-qe-pYd"/>
+                    </layoutGuides>
+                    <view key="view" contentMode="scaleToFill" id="a4n-1z-obZ">
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <wkWebView opaque="NO" tag="11" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="xlZ-tR-6QP">
+                                <rect key="frame" x="20" y="96" width="374" height="758"/>
+                                <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
+                                <wkWebViewConfiguration key="configuration">
+                                    <audiovisualMediaTypes key="mediaTypesRequiringUserActionForPlayback" none="YES"/>
+                                    <wkPreferences key="preferences"/>
+                                </wkWebViewConfiguration>
+                            </wkWebView>
+                        </subviews>
+                        <color key="backgroundColor" red="0.9882352941176471" green="0.98039215686274506" blue="0.81176470588235294" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <constraints>
+                            <constraint firstItem="xlZ-tR-6QP" firstAttribute="trailing" secondItem="a4n-1z-obZ" secondAttribute="trailingMargin" id="GP2-Wr-Bh9"/>
+                            <constraint firstItem="xlZ-tR-6QP" firstAttribute="top" secondItem="TeY-hL-zeC" secondAttribute="bottom" constant="8" symbolic="YES" id="Vvo-yF-z4a"/>
+                            <constraint firstItem="Yrx-qe-pYd" firstAttribute="top" secondItem="xlZ-tR-6QP" secondAttribute="bottom" constant="8" symbolic="YES" id="afC-pF-Eom"/>
+                            <constraint firstItem="xlZ-tR-6QP" firstAttribute="leading" secondItem="a4n-1z-obZ" secondAttribute="leadingMargin" id="wxq-1W-9XD"/>
+                        </constraints>
+                    </view>
+                    <navigationItem key="navigationItem" title="Documentation" id="lf7-H3-aZF"/>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="HMz-gF-Hp5" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="1724.6305418719212" y="384.80000000000001"/>
+        </scene>
+        <!--Ivy Controller-->
+        <scene sceneID="tne-QT-ifu">
+            <objects>
+                <viewController title="Ivy Controller" id="BYZ-38-t0r" customClass="IvyController" sceneMemberID="viewController">
+                    <layoutGuides>
+                        <viewControllerLayoutGuide type="top" id="y3c-jy-aDJ"/>
+                        <viewControllerLayoutGuide type="bottom" id="wfy-db-euE"/>
+                    </layoutGuides>
+                    <view key="view" contentMode="scaleAspectFit" id="8bC-Xf-vdC">
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <stackView opaque="NO" contentMode="scaleToFill" horizontalCompressionResistancePriority="1000" verticalCompressionResistancePriority="1000" alignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="Cn1-rU-W3R">
+                                <rect key="frame" x="20" y="831" width="374" height="31"/>
+                                <subviews>
+                                    <textField opaque="NO" clipsSubviews="YES" tag="1" contentMode="scaleToFill" horizontalHuggingPriority="249" contentHorizontalAlignment="left" contentVerticalAlignment="center" borderStyle="roundedRect" placeholder="Type an expression" minimumFontSize="17" clearButtonMode="whileEditing" translatesAutoresizingMaskIntoConstraints="NO" id="9SS-TP-C7c" userLabel="InputField">
+                                        <rect key="frame" x="0.0" y="0.0" width="301.5" height="31"/>
+                                        <color key="backgroundColor" red="0.98823529409999999" green="0.98039215690000003" blue="0.81176470590000005" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                                        <rect key="contentStretch" x="1" y="1" width="1" height="1"/>
+                                        <fontDescription key="fontDescription" name="Menlo-Bold" family="Menlo" pointSize="14"/>
+                                        <textInputTraits key="textInputTraits" autocorrectionType="no" spellCheckingType="no" keyboardType="alphabet" keyboardAppearance="alert" enablesReturnKeyAutomatically="YES" smartDashesType="no" smartInsertDeleteType="no" smartQuotesType="no"/>
+                                        <connections>
+                                            <action selector="okPressed:" destination="BYZ-38-t0r" eventType="primaryActionTriggered" id="3BK-xS-ize"/>
+                                            <action selector="okPressed:" destination="BYZ-38-t0r" eventType="editingDidEnd" id="91o-Gh-hrf"/>
+                                        </connections>
+                                    </textField>
+                                    <button opaque="NO" contentMode="scaleToFill" horizontalCompressionResistancePriority="1000" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eO6-bM-CwW">
+                                        <rect key="frame" x="301.5" y="0.0" width="72.5" height="31"/>
+                                        <accessibility key="accessibilityConfiguration" label="OK"/>
+                                        <constraints>
+                                            <constraint firstAttribute="height" constant="31" id="1nb-CV-bfg"/>
+                                        </constraints>
+                                        <inset key="imageEdgeInsets" minX="0.0" minY="0.0" maxX="2.2250738585072014e-308" maxY="0.0"/>
+                                        <state key="normal" title="Button" image="return" catalog="system"/>
+                                        <connections>
+                                            <action selector="okPressed:" destination="BYZ-38-t0r" eventType="touchUpInside" id="258-zN-fwW"/>
+                                        </connections>
+                                    </button>
+                                </subviews>
+                                <constraints>
+                                    <constraint firstItem="9SS-TP-C7c" firstAttribute="trailing" secondItem="eO6-bM-CwW" secondAttribute="leading" id="9Fe-Sf-U5p"/>
+                                    <constraint firstItem="eO6-bM-CwW" firstAttribute="top" secondItem="9SS-TP-C7c" secondAttribute="top" id="9hv-aL-4z2"/>
+                                    <constraint firstItem="eO6-bM-CwW" firstAttribute="trailing" secondItem="Cn1-rU-W3R" secondAttribute="trailing" id="A4G-YY-4Gn"/>
+                                    <constraint firstItem="9SS-TP-C7c" firstAttribute="leading" secondItem="Cn1-rU-W3R" secondAttribute="leading" id="i2m-BU-Q4a"/>
+                                </constraints>
+                            </stackView>
+                            <wkWebView opaque="NO" tag="2" contentMode="scaleToFill" preservesSuperviewLayoutMargins="YES" layoutMarginsFollowReadableWidth="YES" translatesAutoresizingMaskIntoConstraints="NO" id="ga1-Py-9re">
+                                <rect key="frame" x="20" y="88" width="374" height="737"/>
+                                <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
+                                <wkWebViewConfiguration key="configuration">
+                                    <audiovisualMediaTypes key="mediaTypesRequiringUserActionForPlayback" none="YES"/>
+                                    <wkPreferences key="preferences"/>
+                                </wkWebViewConfiguration>
+                            </wkWebView>
+                        </subviews>
+                        <color key="backgroundColor" red="0.9882352941176471" green="0.98039215686274506" blue="0.81176470588235294" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <constraints>
+                            <constraint firstItem="Cn1-rU-W3R" firstAttribute="trailing" secondItem="8bC-Xf-vdC" secondAttribute="trailingMargin" id="7DU-Hc-uk7"/>
+                            <constraint firstItem="Cn1-rU-W3R" firstAttribute="bottom" secondItem="wfy-db-euE" secondAttribute="top" id="8mr-vY-R1v"/>
+                            <constraint firstItem="ga1-Py-9re" firstAttribute="bottom" secondItem="Cn1-rU-W3R" secondAttribute="top" constant="-6" id="BX0-OH-IJ4"/>
+                            <constraint firstItem="ga1-Py-9re" firstAttribute="trailing" secondItem="8bC-Xf-vdC" secondAttribute="trailingMargin" id="Fxh-TE-BtG"/>
+                            <constraint firstItem="Cn1-rU-W3R" firstAttribute="leading" secondItem="8bC-Xf-vdC" secondAttribute="leadingMargin" id="LPE-LO-nct"/>
+                            <constraint firstItem="ga1-Py-9re" firstAttribute="top" secondItem="8bC-Xf-vdC" secondAttribute="topMargin" id="p9M-sp-ZwC"/>
+                            <constraint firstItem="ga1-Py-9re" firstAttribute="leading" secondItem="8bC-Xf-vdC" secondAttribute="leadingMargin" id="pOi-3s-hrr"/>
+                        </constraints>
+                    </view>
+                    <navigationItem key="navigationItem" title="Ivy" id="9fD-A5-WTg">
+                        <barButtonItem key="leftBarButtonItem" title="Clear" id="70x-xp-aiX">
+                            <connections>
+                                <action selector="clear:" destination="BYZ-38-t0r" id="n7k-fg-dil"/>
+                            </connections>
+                        </barButtonItem>
+                        <rightBarButtonItems>
+                            <barButtonItem title="Help" id="aDa-GJ-VpX">
+                                <connections>
+                                    <segue destination="rfr-rm-AXI" kind="show" id="kuc-xA-dyM"/>
+                                </connections>
+                            </barButtonItem>
+                            <barButtonItem title="Demo" id="ZN2-PQ-aPW">
+                                <connections>
+                                    <action selector="demo:" destination="BYZ-38-t0r" id="NpG-yh-wMO"/>
+                                </connections>
+                            </barButtonItem>
+                        </rightBarButtonItems>
+                    </navigationItem>
+                    <connections>
+                        <outlet property="bottomConstraint" destination="8mr-vY-R1v" id="BqX-Do-vtq"/>
+                        <outlet property="input" destination="9SS-TP-C7c" id="jUA-25-4WI"/>
+                        <outlet property="okButton" destination="eO6-bM-CwW" id="o9U-hD-NDr"/>
+                        <outlet property="tape" destination="ga1-Py-9re" id="00M-9S-MAl"/>
+                    </connections>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="989.85507246376824" y="382.36607142857139"/>
+        </scene>
+        <!--Navigation Controller-->
+        <scene sceneID="ZgV-45-Pf8">
+            <objects>
+                <navigationController automaticallyAdjustsScrollViewInsets="NO" id="mTw-C8-NzX" sceneMemberID="viewController">
+                    <toolbarItems/>
+                    <navigationBar key="navigationBar" opaque="NO" contentMode="scaleToFill" id="aev-Tm-XK3">
+                        <rect key="frame" x="0.0" y="44" width="414" height="44"/>
+                        <autoresizingMask key="autoresizingMask"/>
+                        <color key="backgroundColor" red="1" green="1" blue="0.80392156859999997" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <color key="barTintColor" red="1" green="1" blue="0.80392156859999997" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <navigationBarAppearance key="standardAppearance">
+                            <color key="backgroundColor" red="1" green="1" blue="0.80392156859999997" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        </navigationBarAppearance>
+                        <navigationBarAppearance key="compactAppearance">
+                            <color key="backgroundColor" red="1" green="1" blue="0.80392156859999997" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        </navigationBarAppearance>
+                        <navigationBarAppearance key="scrollEdgeAppearance">
+                            <color key="backgroundColor" red="1" green="1" blue="0.80392156859999997" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        </navigationBarAppearance>
+                    </navigationBar>
+                    <nil name="viewControllers"/>
+                    <toolbar key="toolbar" opaque="NO" clearsContextBeforeDrawing="NO" contentMode="scaleToFill" insetsLayoutMarginsFromSafeArea="NO" id="smI-B7-WbU">
+                        <autoresizingMask key="autoresizingMask"/>
+                    </toolbar>
+                    <connections>
+                        <segue destination="BYZ-38-t0r" kind="relationship" relationship="rootViewController" id="Nyy-d4-AXi"/>
+                    </connections>
+                </navigationController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="i1l-Sg-DC5" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="271" y="386"/>
+        </scene>
+    </scenes>
+    <resources>
+        <image name="return" catalog="system" width="128" height="101"/>
+    </resources>
+</document>
--- a/example/ivy/ios/ivy/DocsController.h
+++ b/example/ivy/ios/ivy/DocsController.h
@ -0,0 +1,11 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import <WebKit/WebKit.h>
+
+// DocsController displays the documentation page.
+@interface DocsController : UIViewController
+
+@end
+
--- a/example/ivy/ios/ivy/DocsController.m
+++ b/example/ivy/ios/ivy/DocsController.m
@ -0,0 +1,42 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import "DocsController.h"
+#import "mobile/Mobile.h"
+
+@interface DocsController () {
+  WKWebView *webView;
+}
+
+@end
+
+@implementation DocsController
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+  webView = (WKWebView *)[self.view viewWithTag:11];
+  NSString *helpHTML = MobileHelp();
+  NSRange r = [helpHTML rangeOfString:@"<head>"];
+  NSString *html = [helpHTML substringToIndex:r.location];
+
+  // With the following meta tag, WKWebView displays the fonts more nicely.
+  NSString *meta = @"<meta name='viewport' \
+        content='width=device-width, "
+                   @"initial-scale=1.0, maximum-scale=1.0, \
+        minimum-scale=1.0, "
+                   @"user-scalable=no'>";
+
+  html = [html stringByAppendingString:@"<head>"];
+  html = [html stringByAppendingString:meta];
+  html = [html stringByAppendingString:[helpHTML substringFromIndex:r.location]];
+
+  [webView loadHTMLString:html baseURL:NULL];
+}
+
+- (void)didReceiveMemoryWarning {
+  [super didReceiveMemoryWarning];
+}
+
+@end
+
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/Contents.json
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/Contents.json
@ -0,0 +1,300 @@
+{
+  "images" : [
+    {
+      "filename" : "icon-40.png",
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "20x20"
+    },
+    {
+      "filename" : "icon-60.png",
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "20x20"
+    },
+    {
+      "filename" : "icon-58.png",
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "29x29"
+    },
+    {
+      "filename" : "icon-87.png",
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "29x29"
+    },
+    {
+      "filename" : "icon-80.png",
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "40x40"
+    },
+    {
+      "filename" : "icon-120.png",
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "40x40"
+    },
+    {
+      "filename" : "icon-120.png",
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "60x60"
+    },
+    {
+      "filename" : "icon-180.png",
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "60x60"
+    },
+    {
+      "filename" : "icon-20.png",
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "20x20"
+    },
+    {
+      "filename" : "icon-40.png",
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "20x20"
+    },
+    {
+      "filename" : "icon-29.png",
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "29x29"
+    },
+    {
+      "filename" : "icon-58.png",
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "29x29"
+    },
+    {
+      "filename" : "icon-40.png",
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "40x40"
+    },
+    {
+      "filename" : "icon-80.png",
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "40x40"
+    },
+    {
+      "filename" : "icon-76.png",
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "76x76"
+    },
+    {
+      "filename" : "icon-152.png",
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "76x76"
+    },
+    {
+      "filename" : "icon-167.png",
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "83.5x83.5"
+    },
+    {
+      "filename" : "icon-1024.png",
+      "idiom" : "ios-marketing",
+      "scale" : "1x",
+      "size" : "1024x1024"
+    },
+    {
+      "filename" : "icon-120.png",
+      "idiom" : "car",
+      "scale" : "2x",
+      "size" : "60x60"
+    },
+    {
+      "filename" : "icon-180.png",
+      "idiom" : "car",
+      "scale" : "3x",
+      "size" : "60x60"
+    },
+    {
+      "filename" : "icon-48.png",
+      "idiom" : "watch",
+      "role" : "notificationCenter",
+      "scale" : "2x",
+      "size" : "24x24",
+      "subtype" : "38mm"
+    },
+    {
+      "filename" : "icon-55.png",
+      "idiom" : "watch",
+      "role" : "notificationCenter",
+      "scale" : "2x",
+      "size" : "27.5x27.5",
+      "subtype" : "42mm"
+    },
+    {
+      "filename" : "icon-58.png",
+      "idiom" : "watch",
+      "role" : "companionSettings",
+      "scale" : "2x",
+      "size" : "29x29"
+    },
+    {
+      "filename" : "icon-87.png",
+      "idiom" : "watch",
+      "role" : "companionSettings",
+      "scale" : "3x",
+      "size" : "29x29"
+    },
+    {
+      "idiom" : "watch",
+      "role" : "notificationCenter",
+      "scale" : "2x",
+      "size" : "33x33",
+      "subtype" : "45mm"
+    },
+    {
+      "filename" : "icon-80.png",
+      "idiom" : "watch",
+      "role" : "appLauncher",
+      "scale" : "2x",
+      "size" : "40x40",
+      "subtype" : "38mm"
+    },
+    {
+      "filename" : "icon-88.png",
+      "idiom" : "watch",
+      "role" : "appLauncher",
+      "scale" : "2x",
+      "size" : "44x44",
+      "subtype" : "40mm"
+    },
+    {
+      "idiom" : "watch",
+      "role" : "appLauncher",
+      "scale" : "2x",
+      "size" : "46x46",
+      "subtype" : "41mm"
+    },
+    {
+      "filename" : "icon-100.png",
+      "idiom" : "watch",
+      "role" : "appLauncher",
+      "scale" : "2x",
+      "size" : "50x50",
+      "subtype" : "44mm"
+    },
+    {
+      "idiom" : "watch",
+      "role" : "appLauncher",
+      "scale" : "2x",
+      "size" : "51x51",
+      "subtype" : "45mm"
+    },
+    {
+      "filename" : "icon-172.png",
+      "idiom" : "watch",
+      "role" : "quickLook",
+      "scale" : "2x",
+      "size" : "86x86",
+      "subtype" : "38mm"
+    },
+    {
+      "filename" : "icon-196.png",
+      "idiom" : "watch",
+      "role" : "quickLook",
+      "scale" : "2x",
+      "size" : "98x98",
+      "subtype" : "42mm"
+    },
+    {
+      "filename" : "icon-216.png",
+      "idiom" : "watch",
+      "role" : "quickLook",
+      "scale" : "2x",
+      "size" : "108x108",
+      "subtype" : "44mm"
+    },
+    {
+      "idiom" : "watch",
+      "role" : "quickLook",
+      "scale" : "2x",
+      "size" : "117x117",
+      "subtype" : "45mm"
+    },
+    {
+      "filename" : "icon-1024.png",
+      "idiom" : "watch-marketing",
+      "scale" : "1x",
+      "size" : "1024x1024"
+    },
+    {
+      "filename" : "icon-16.png",
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "16x16"
+    },
+    {
+      "filename" : "icon-32.png",
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "16x16"
+    },
+    {
+      "filename" : "icon-32.png",
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "32x32"
+    },
+    {
+      "filename" : "icon-64.png",
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "32x32"
+    },
+    {
+      "filename" : "icon-128.png",
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "128x128"
+    },
+    {
+      "filename" : "icon-256.png",
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "128x128"
+    },
+    {
+      "filename" : "icon-256.png",
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "256x256"
+    },
+    {
+      "filename" : "icon-512.png",
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "256x256"
+    },
+    {
+      "filename" : "icon-512.png",
+      "idiom" : "mac",
+      "scale" : "1x",
+      "size" : "512x512"
+    },
+    {
+      "filename" : "icon-1024.png",
+      "idiom" : "mac",
+      "scale" : "2x",
+      "size" : "512x512"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-100.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-100.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-1024.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-1024.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-120.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-120.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-128.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-128.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-152.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-152.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-16.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-16.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-167.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-167.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-172.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-172.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-180.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-180.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-196.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-196.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-20.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-20.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-216.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-216.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-256.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-256.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-29.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-29.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-32.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-32.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-40.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-40.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-48.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-48.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-512.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-512.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-55.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-55.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-58.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-58.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-60.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-60.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-64.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-64.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-76.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-76.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-80.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-80.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-87.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-87.png
--- a/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-88.png
+++ b/example/ivy/ios/ivy/Images.xcassets/AppIcon.appiconset/icon-88.png
--- a/example/ivy/ios/ivy/Info.plist
+++ b/example/ivy/ios/ivy/Info.plist
@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>UIUserInterfaceStyle</key>
+	<string>Light</string>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleDisplayName</key>
+	<string>Ivy</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>com.google.$(PRODUCT_NAME:rfc1034identifier)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>6</string>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>UILaunchStoryboardName</key>
+	<string>Launch</string>
+	<key>UIMainStoryboardFile</key>
+	<string>Main</string>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array/>
+	<key>UIRequiresFullScreen</key>
+	<false/>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+</dict>
+</plist>
--- a/example/ivy/ios/ivy/IvyController.h
+++ b/example/ivy/ios/ivy/IvyController.h
@ -0,0 +1,25 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import <UIKit/UIKit.h>
+#import <WebKit/WebKit.h>
+#import "Suggestion.h"
+
+// IvyController displays the main app view.
+@interface IvyController : UIViewController <UITextFieldDelegate, WKUIDelegate, SuggestionDelegate>
+
+@property(weak, nonatomic) IBOutlet NSLayoutConstraint *bottomConstraint;
+
+// A text input field coupled to an output "tape", rendered with a WKWebView.
+@property(weak, nonatomic) IBOutlet UITextField *input;
+@property(strong, nonatomic) Suggestion *suggestionView;
+@property(weak, nonatomic) IBOutlet WKWebView *tape;
+@property(weak, nonatomic) IBOutlet UIButton *okButton;
+
+- (IBAction)clear:(id)sender;
+- (IBAction)demo:(id)sender;
+- (IBAction)okPressed:(id)sender;
+
+@end
+
--- a/example/ivy/ios/ivy/IvyController.m
+++ b/example/ivy/ios/ivy/IvyController.m
@ -0,0 +1,216 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import "IvyController.h"
+#import "mobile/Mobile.h"
+
+@interface IvyController ()
+
+@end
+
+@implementation IvyController {
+  NSArray *demo_lines;
+  int demo_index;
+}
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+
+  self.input.delegate = self;
+  self.input.autocorrectionType = UITextAutocorrectionTypeNo;
+  self.input.keyboardType = UIKeyboardTypeNumbersAndPunctuation;
+
+  self.suggestionView = [[Suggestion alloc] init];
+  self.suggestionView.delegate = self;
+
+  self.tape.UIDelegate = self;
+  self->demo_lines = NULL;
+
+  [self.okButton setTitle:@"" forState:UIControlStateNormal];
+  [self.okButton setHidden:TRUE];
+
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(textDidChange:)
+                                               name:UITextFieldTextDidChangeNotification
+                                             object:self.input];
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(keyboardWillShow:)
+                                               name:UIKeyboardWillShowNotification
+                                             object:nil];
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(keyboardWillHide:)
+                                               name:UIKeyboardWillHideNotification
+                                             object:nil];
+
+  [self.input becomeFirstResponder];
+  [self clear:NULL];
+}
+
+- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
+  if ([textField isEqual:self.input]) {
+    textField.inputAccessoryView = self.suggestionView;
+    textField.autocorrectionType = UITextAutocorrectionTypeNo;
+    [textField reloadInputViews];
+  }
+  return YES;
+}
+
+- (BOOL)textFieldShouldEndEditing:(UITextField *)textField {
+  if ([textField isEqual:self.input]) {
+    textField.inputAccessoryView = nil;
+    [textField reloadInputViews];
+  }
+  return YES;
+}
+
+- (void)textDidChange:(NSNotification *)notif {
+  [self.suggestionView suggestFor:self.input.text];
+}
+
+- (void)suggestionReplace:(NSString *)text {
+  self.input.text = text;
+  [self.suggestionView suggestFor:text];
+}
+
+- (void)keyboardWillShow:(NSNotification *)aNotification {
+  // Move the input text field up, as the keyboard has taken some of the screen.
+  NSDictionary *info = [aNotification userInfo];
+  CGRect kbFrame = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
+  NSNumber *duration = [info objectForKey:UIKeyboardAnimationDurationUserInfoKey];
+
+  UIViewAnimationCurve keyboardTransitionAnimationCurve;
+  [[info valueForKey:UIKeyboardAnimationCurveUserInfoKey]
+      getValue:&keyboardTransitionAnimationCurve];
+  UIViewAnimationOptions options =
+      keyboardTransitionAnimationCurve | keyboardTransitionAnimationCurve << 16;
+
+  [UIView animateWithDuration:duration.floatValue
+      delay:0
+      options:options
+      animations:^{
+        self.bottomConstraint.constant = 0 - kbFrame.size.height;
+        [self.view layoutIfNeeded];
+      }
+      completion:^(BOOL finished) {
+        [self scrollTapeToBottom];
+      }];
+}
+
+- (void)keyboardWillHide:(NSNotification *)aNotification {
+  // Move the input text field back down.
+  NSDictionary *info = [aNotification userInfo];
+
+  NSNumber *duration = [info objectForKey:UIKeyboardAnimationDurationUserInfoKey];
+
+  UIViewAnimationCurve keyboardTransitionAnimationCurve;
+  [[info valueForKey:UIKeyboardAnimationCurveUserInfoKey]
+      getValue:&keyboardTransitionAnimationCurve];
+  UIViewAnimationOptions options =
+      keyboardTransitionAnimationCurve | keyboardTransitionAnimationCurve << 16;
+
+  int offset = self.input.inputAccessoryView != NULL ? self.suggestionView.frame.size.height : 0;
+
+  [UIView animateWithDuration:duration.floatValue
+      delay:0
+      options:options
+      animations:^{
+        self.bottomConstraint.constant = 0 - offset;
+        [self.view layoutIfNeeded];
+      }
+      completion:^(BOOL finished) {
+        [self scrollTapeToBottom];
+      }];
+}
+
+- (void)enterPressed {
+  NSString *text = self.input.text;
+  if ([text isEqual:@""]) {
+    if (self->demo_lines == NULL) {
+      return;
+    }
+    while (demo_index < self->demo_lines.count) {
+      NSString *line = self->demo_lines[self->demo_index++];
+      if ([line hasPrefix:@"#"]) {
+        [self appendTape:line tag:@"comment"];
+      } else {
+        self.input.text = line;
+        break;
+      }
+    }
+  } else if (self->demo_lines != NULL && [text isEqual:@"quit"]) {
+    [self unloadDemo];
+  } else {
+    [self appendTape:text tag:@"expr"];
+    NSString *expr = [text stringByAppendingString:@"\n"];
+    NSError *err;
+    NSString *result = MobileEval(expr, &err);
+    if (err != nil) {
+      result = err.description;
+    }
+    result = [result stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]];
+    result = [result stringByReplacingOccurrencesOfString:@"<" withString:@"&lt;"];
+    result = [result stringByReplacingOccurrencesOfString:@">" withString:@"&gt;"];
+    NSMutableArray *lines = (NSMutableArray *)[result componentsSeparatedByString:@"\n"];
+    for (NSMutableString *line in lines) {
+      if ([line hasPrefix:@"#"])
+        [self appendTape:line tag:@"comment"];
+      else
+        [self appendTape:line tag:@"result"];
+    }
+    self.input.text = @"";
+  }
+  [self.input becomeFirstResponder];
+}
+
+- (void)scrollTapeToBottom {
+  NSString *scroll = @"window.scrollBy(0, document.body.offsetHeight);";
+  [self.tape evaluateJavaScript:scroll completionHandler:nil];
+}
+
+- (void)appendTape:(NSString *)text tag:(NSString *)tag {
+  NSString *injectSrc = @"appendDiv('%@','%@');";
+  NSString *runToInject = [NSString stringWithFormat:injectSrc, text, tag];
+  [self.tape evaluateJavaScript:runToInject completionHandler:nil];
+  [self scrollTapeToBottom];
+}
+
+- (void)loadDemo {
+  [self.okButton setHidden:FALSE];
+  NSString *text = DemoText();
+
+  self->demo_lines =
+      [text componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];
+  self->demo_index = 0;
+  self.input.text = @"";
+  self.input.enablesReturnKeyAutomatically = TRUE;
+  [self enterPressed];
+}
+- (void)unloadDemo {
+  [self.okButton setHidden:TRUE];
+  self.input.enablesReturnKeyAutomatically = FALSE;
+  self->demo_lines = NULL;
+  self.input.text = @"";
+}
+- (IBAction)okPressed:(id)sender {
+  [self enterPressed];
+}
+
+- (IBAction)demo:(id)sender {
+  if (self->demo_lines) {  // demo already running
+    [self enterPressed];
+  } else {
+    [self loadDemo];
+  }
+}
+
+- (IBAction)clear:(id)sender {
+  [self unloadDemo];
+  NSString *string = [NSString
+      stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"tape" ofType:@"html"]
+                      encoding:NSUTF8StringEncoding
+                         error:NULL];
+  [self.tape loadHTMLString:string baseURL:NULL];
+}
+@end
+
--- a/example/ivy/ios/ivy/Suggestion.h
+++ b/example/ivy/ios/ivy/Suggestion.h
@ -0,0 +1,22 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import <UIKit/UIKit.h>
+
+@protocol SuggestionDelegate <NSObject>
+
+@required
+- (void)suggestionReplace:(NSString *)text;
+@end
+
+@interface Suggestion : UIInputView
+
+- (instancetype)init;
+- (instancetype)initWithFrame:(CGRect)frame;
+- (void)suggestFor:(NSString *)text;
+
+@property(weak) id<SuggestionDelegate> delegate;
+
+@end
+
--- a/example/ivy/ios/ivy/Suggestion.m
+++ b/example/ivy/ios/ivy/Suggestion.m
@ -0,0 +1,164 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#import "Suggestion.h"
+
+#define maxSuggestions 4 + 3
+
+@implementation Suggestion {
+  NSString *text;
+  NSRange range;
+
+  NSMutableOrderedSet *options;
+  NSMutableArray *buttons;
+  NSArray *possibleSuggestions;
+  NSCharacterSet *breakingChars;
+}
+
+- (instancetype)init {
+  CGFloat screenWidth = [UIScreen mainScreen].bounds.size.width;
+  self = [self initWithFrame:CGRectMake(0.0f, 0.0f, screenWidth, 36.0f)];
+  return self;
+}
+
+- (instancetype)initWithFrame:(CGRect)frame {
+  self = [super initWithFrame:frame inputViewStyle:UIInputViewStyleKeyboard];
+  if (self) {
+    possibleSuggestions = @[
+      @")base ", @")debug ", @")format ", @")maxdigits ", @")op ", @")origin ", @")prec ",
+      @")prompt ", @")seed ", @"cos ", @"iota ", @"log ", @"max ", @"min ", @"pi ", @"rho ",
+      @"sin ", @"sqrt ", @"tan "
+    ];
+    breakingChars = [NSCharacterSet characterSetWithCharactersInString:@"/+-*,^|= "];
+    options = [[NSMutableOrderedSet alloc] initWithCapacity:maxSuggestions];
+    buttons = [[NSMutableArray alloc] init];
+    self.backgroundColor = [UIColor colorWithWhite:0.0f alpha:0.05f];
+    [self setSuggestions:nil];
+  }
+  return self;
+}
+
+- (void)suggestFor:(NSString *)t {
+  text = t;
+  range = [text rangeOfCharacterFromSet:breakingChars options:NSBackwardsSearch];
+  if (range.location == NSNotFound) {
+    range.location = 0;
+    range.length = text.length;
+  } else {
+    if (range.location > 0 && [text characterAtIndex:range.location - 1] == ')') {
+      // Special case for suggestions that start with ") ".
+      range.location -= 1;
+      range.length++;
+    } else {
+      range.location += 1;
+      range.length -= 0;
+    }
+  }
+  range.length = text.length - range.location;
+  if (range.length == 0) {
+    [self setSuggestions:nil];
+  } else {
+    NSString *prefix = [text substringWithRange:range];
+    // TODO: make not so slow.
+    NSArray *suggestions = @[];
+    for (NSString *suggestion in possibleSuggestions) {
+      if ([suggestion hasPrefix:prefix] && prefix.length < suggestion.length) {
+        suggestions = [suggestions arrayByAddingObject:suggestion];
+      }
+    }
+    if (suggestions.count > 3) {
+      suggestions = nil;
+    }
+    [self setSuggestions:suggestions];
+  }
+  [self setNeedsLayout];
+}
+
+- (void)setSuggestions:(NSArray *)suggestions {
+  [options removeAllObjects];
+
+  if ([suggestions respondsToSelector:@selector(countByEnumeratingWithState:objects:count:)]) {
+    for (NSString *suggestion in suggestions) {
+      if (options.count < maxSuggestions) {
+        [options addObject:suggestion];
+      } else {
+        break;
+      }
+    }
+  }
+}
+
+- (void)layoutSubview:(NSString *)t at:(CGFloat)x width:(CGFloat)w {
+  UIButton *b = [[UIButton alloc] initWithFrame:CGRectMake(x, 0.0f, w, self.bounds.size.height)];
+  [b setTitle:t forState:UIControlStateNormal];
+  b.titleLabel.adjustsFontSizeToFitWidth = YES;
+  b.titleLabel.textAlignment = NSTextAlignmentCenter;
+  [b setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
+  [b addTarget:self action:@selector(buttonTouched:) forControlEvents:UIControlEventTouchUpInside];
+  [self addSubview:b];
+
+  if (x > 0) {
+    UIView *line =
+        [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 0.5f, self.bounds.size.height)];
+    line.backgroundColor = [UIColor colorWithRed:0.984 green:0.977 blue:0.81 alpha:1.0];
+    [b addSubview:line];
+  }
+
+  [buttons addObject:b];
+}
+
+- (void)layoutSubviews {
+  for (UIView *subview in buttons) {
+    [subview removeFromSuperview];
+  }
+  [buttons removeAllObjects];
+
+  CGFloat symbolWidth = 40.0f;
+  [self layoutSubview:@"+" at:0 * symbolWidth width:symbolWidth];
+  [self layoutSubview:@"-" at:1 * symbolWidth width:symbolWidth];
+  [self layoutSubview:@"*" at:2 * symbolWidth width:symbolWidth];
+  [self layoutSubview:@"/" at:3 * symbolWidth width:symbolWidth];
+
+  for (int i = 0; i < options.count; i++) {
+    NSString *suggestion = options[i];
+    CGFloat width = (self.bounds.size.width - (4 * symbolWidth)) / options.count;
+    CGFloat x = (4 * symbolWidth) + (i * width);
+    [self layoutSubview:suggestion at:x width:width];
+  }
+}
+
+- (void)buttonTouched:(UIButton *)button {
+  NSTimeInterval duration = 0.08f;
+  [UIView animateWithDuration:duration
+                   animations:^{
+                     [button setBackgroundColor:[UIColor whiteColor]];
+
+                     if ([self.delegate respondsToSelector:@selector(suggestionReplace:)]) {
+                       NSString *t = self->text;
+                       if (t == nil) {
+                         t = @"";
+                       }
+                       if (button.currentTitle.length == 1) {
+                         // Special case for +, -, *, /.
+                         t = [t stringByAppendingString:button.currentTitle];
+                       } else {
+                         t = [self->text stringByReplacingCharactersInRange:self->range
+                                                                 withString:button.currentTitle];
+                       }
+                       [self performSelector:@selector(suggestionReplace:)
+                                  withObject:t
+                                  afterDelay:duration * 0.8f];
+                     }
+                     [button performSelector:@selector(setBackgroundColor:)
+                                  withObject:[UIColor clearColor]
+                                  afterDelay:duration];
+                   }];
+}
+
+- (void)suggestionReplace:(NSString *)t {
+  [self.delegate performSelector:@selector(suggestionReplace:) withObject:t];
+}
+
+@end
+
--- a/example/ivy/ios/ivy/en.lproj/Main.strings
+++ b/example/ivy/ios/ivy/en.lproj/Main.strings
@ -0,0 +1,18 @@
+
+/* Class = "UITextField"; placeholder = "Type an expression"; ObjectID = "9SS-TP-C7c"; */
+"9SS-TP-C7c.placeholder" = "Type an expression";
+
+/* Class = "UIViewController"; title = "Ivy Controller"; ObjectID = "BYZ-38-t0r"; */
+"BYZ-38-t0r.title" = "Ivy Controller";
+
+/* Class = "UIBarButtonItem"; title = "Help"; ObjectID = "GSn-BW-al6"; */
+"GSn-BW-al6.title" = "Help";
+
+/* Class = "UINavigationItem"; title = "Ivy"; ObjectID = "KhW-J4-UcU"; */
+"KhW-J4-UcU.title" = "Ivy";
+
+/* Class = "UINavigationItem"; title = "Documentation"; ObjectID = "lf7-H3-aZF"; */
+"lf7-H3-aZF.title" = "Documentation";
+
+/* Class = "UIViewController"; title = "Docs"; ObjectID = "rfr-rm-AXI"; */
+"rfr-rm-AXI.title" = "Docs";
--- a/example/ivy/ios/ivy/main.m
+++ b/example/ivy/ios/ivy/main.m
@ -0,0 +1,11 @@
+#import <UIKit/UIKit.h>
+#import "AppDelegate.h"
+
+int main(int argc, char *argv[])
+{
+    @autoreleasepool
+    {
+        return UIApplicationMain(argc, argv, nil,
+                                 NSStringFromClass([AppDelegate class]));
+    }
+}
--- a/Show more
+++ b/Show more