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Cargo-mobile for Wry

We evaluate cargo-mobile to create a mobile project for both Xcode and Android studio.Right now it provides two templates tauri (iOS only at the moment) and wry (both iOS and Android).

Prerequisite

  • Works on Linux, Windows, macOS, and WSL(Windows subsystem for Linux).
  • Xcode and Android Studio installed properly. This is the most difficult part imho. This means all toolchains and SDK are all installed.

Setting up Android Environment

1. Installing JDK

Using Android Studio:

If you have Android Studio installed, it ships with a version of JDK so you don't have to install it manually. It is usually at <location of android studio installation>/jre and can be used for JAVA_HOME env var.

you can find it on Windows at C:\Program Files\Android\Android Studio\jre

Using the terminal:

Linux/WSL

  • Install it by running the following command based on your distro to install JDK:

    • debian 
      ​​​​​​​​sudo apt install default-jdk
    • arch (I use arch btw) 
      ​​​​​​​​sudo pacman -S jdk-openjdk

  • Set the JAVA_HOME env variable for this current shell (we will make it permanent later on)

    ​​​​export JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64"

macOS

  • Install openjdk from Homebrew:
brew install openjdk
  • Link to system Java wrapper and set the JAVA_HOME env:
sudo ln -sfn /opt/homebrew/opt/openjdk/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk.jdk
export JAVA_HOME="/Library/Java/JavaVirtualMachines/openjdk.jdk/Contents/Home"
Windows
  • Download openjdk-11 
    ​​​​cd $HOME\downloads
​​​​Invoke-WebRequest https://download.java.net/java/GA/jdk11/9/GPL/openjdk-11.0.2_windows-x64_bin.zip -o openjdk-11.zip
​​​​Expand-Archive openjdk-11.zip -d .
​​​​mkdir $env:LocalAppData\Java
​​​​mv jdk-11.0.2 $env:LocalAppData\Java
  • Set the JAVA_HOME env variable for this current shell (we will make it permanent later on) 
    ​​​​$env:JAVA_HOME="$env:LocalAppData\Java\jdk-11.0.2"

2. Installing Android SDK and NDK

There is two ways to install the sdk and ndk.

Using Android Studio:

You can use the SDK Manager in Android Studio to install:

Note: you may need to tick Show Package Details in the right bottom corner to be able to see some of these components

  1. Android Sdk Platform 33
  2. Android SDK Platform-Tools
  3. NDK (Side by side) 25.0.8775105
  4. Android SDK Build-Tools 33.0.
  5. Android SDK Command-line Tools

Using the terminal:

If you don't want or can't use Android Studio you can still get the SDK Manager cli quite easily and use it to install other components.

Note: The SDK Manager is part of the "Command line tools only" that can be downloaded from here

Linux/WSL/macOS

Download the cmdline-tools

cd ~/Downloads

# if you are on Linux/WSL:
wget https://dl.google.com/android/repository/commandlinetools-linux-8512546_latest.zip -O  
# if you are on macos: 
wget https://dl.google.com/android/repository/commandlinetools-mac-8512546_latest.zip -O

unzip cmdline-tools.zip
cd cmdline-tools
mkdir latest
mv bin latest/
mv lib latest/
mv NOTICE.txt latest/
mv source.properties latest/
cd ..
mkdir ~/.android # You can use another location for your SDK but I prefer using ~/.android
mv cmdline-tools ~/.android

Install required SDK and NDK components

export ANDROID_SDK_ROOT="$HOME/.android"
~/.android/cmdline-tools/latest/bin/sdkmanager "platforms;android-33" "platform-tools" "ndk;25.0.8775105" "build-tools;33.0.0"
Windows

Download the cmdline-tools

cd $HOME\downloads
Invoke-WebRequest https://dl.google.com/android/repository/commandlinetools-win-8512546_latest.zip -o cmdline-tools.zip
Expand-Archive cmdline-tools.zip -d .
cd cmdline-tools
mkdir latest
mv bin latest/
mv lib latest/
mv NOTICE.txt latest/
mv source.properties latest/
cd ..
mkdir $HOME\.android # You can use another location for your SDK but I prefer using $HOME\.android
mv cmdline-tools $HOME\.android

Install required SDK and NDK components

$env:ANDROID_SDK_ROOT="$HOME\.android"
&"$env:ANDROID_SDK_ROOT\cmdline-tools\latest\bin\sdkmanager.exe" "platforms;android-33" "platform-tools" "ndk;25.0.8775105" "build-tools;33.0.0"

Note: the location you moved the cmdline-tools directory into will be the location of your android SDK.

3. Setting up Environment Variables

You'll need to set up some environment variables to get everything to work properly. The environment variables below should be all the ones your need to be able to use cargo-mobile to build/run your android app.

Linux/WSL/macOS
# .bashrc or .zshrc
export JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64" # if you are using Android studio, the location is different, see the section above about JDK
export ANDROID_SDK_ROOT="$HOME/.android" # if you are using Android studio, the sdk location will be at `~/Android/Sdk`
export NDK_HOME="$ANDROID_SDK_ROOT/ndk/25.0.8775105"
export PATH="$PATH:$ANDROID_SDK_ROOT/cmdline-tools/latest/bin"
export PATH="$PATH:$ANDROID_SDK_ROOT/platform-tools"

For WSL:
you also need to get ADB to connect to your emulator that is running on Windows

​​​export WSL_HOST="192.168.1.2" # Run `ipconfig` in windows to get your computer IP
​​​export ADB_SERVER_SOCKET=tcp:$WSL_HOST:5037

After updating .bashrc either run source ~/.bashrc or reopen your terminal to apply the changes.

Windows

Open a powershell instance and run the following commands in order

Function Add-EnvVar($name, $value) { [System.Environment]::SetEnvironmentVariable("$name", "$value", "User") }
Function Add-PATHEntry($path) { $newPath = [System.Environment]::GetEnvironmentVariable("Path", "User") + ";" + $path; [System.Environment]::SetEnvironmentVariable("Path", "$newPath", "User") }

Add-EnvVar JAVA_HOME "$env:LocalAppData\Java\jdk-11.0.2" # if you are using Android studio, the location is different, see the section above about JDK
$env:SDK_ROOT="$HOME\.android"# if you are using Android studio, the sdk location will be at `$env:LocalAppData\Android\Sdk`
Add-EnvVar ANDROID_SDK_ROOT "$env:SDK_ROOT" 
Add-EnvVar NDK_HOME "$env:SDK_ROOT\ndk\25.0.8775105"

Add-PATHEntry "$env:SDK_ROOT\cmdline-tools\latest\bin"
Add-PATHEntry "$env:SDK_ROOT\platform-tools"

IMPORTANT: you need to reboot your Windows machine in order for the environement variables to be loaded correctly.

You should now have all the environment variables required and the cmdline-tools available in your PATH. You can verify this by running sdkmanager which should now be showing its help info.

4. Install Rust android targets:

rustup target add aarch64-linux-android armv7-linux-androideabi i686-linux-android x86_64-linux-android

Getting Started

Now lets bootstrap a project to develop a tauri or wry project for mobile.

  • Install our fork of cargo-mobile by running: 
    ​​​​cargo install --git  https://github.com/tauri-apps/cargo-mobile
  • Create a directory and init the project. 
    ​​​​mkdir hello
​​​​cd hello
​​​​cargo mobile init
​​​​# Project name (hello):
​​​​# Stylized name (Hello):
​​​​# Domain (example.com): tauri.app
​​​​# Detected template packs:
​​​​#   [0] tauri
​​​​#   [1] wry
​​​​#   Enter an index for a template pack above.
​​​​# Template pack (0):

Build and Run on Device

Android

Make sure you're device is connected to adb
you can check by running cargo android list or adb devices

  • cargo android run

iOS

  • cargo apple run

First time running the app will be blocked. Go to your phone's Settings > Privacy & Security > Developer Mode to enable developer mode. Settings -> General -> VPN and device management -> From "Developer App" section found "Apple Development: APPLE_ID" -> Trust

Build and Run on Emulator

Android

Using Android Studio
  • Open the project in Android Studio cargo android open
  • Click Trust Project, Use Embedded JDK
  • (optional?) From my setup, I also need to add abiFilters += listOf("arm64-v8a") under create("arm") branch in :app's 'build.gradle.kts.
  • Choose an emulator. I usually choose Pixel 4 API 32
  • (optional) if you face this error Device supports x86, but APK only supports armeabi-v7a then check this Stack Overflow answer to fix it.
  • Press run button.
Without Android Studio

If you don't have access to Android Studio or don't want or when running in WSL, you can build and run the generated project directly from the terminal

  1. List available emulators
    • Linux/WSL/macOS: 
      ​​​​​$ANDROID_SDK_ROOT/emulator/emulator -list-avds
    • Windows: 
      ​​​​​&"$env:ANDROID_SDK_ROOT\emulator\emulator" -list-avds
    you should now see a list of available emulators like the following, you'll need one of them for the next step: 
    ​​​​Resizable_API_33
​​​​Pixel_5_API_33
  2. Start the emulator with the name of the desired emulator:
    • Linux/WSL/macOS: 
      ​​​​​$ANDROID_SDK_ROOT/emulator/emulator -avd Resizable_API_33
    • Windows: 
      ​​​​​ &"$env:ANDROID_SDK_ROOT\emulator\emulator" -avd Resizable_API_33
  3. In a new terminal window, run: 
    ​​​​cargo android run

iOS

  • If you are on x86_64: cargo build --target x86_64-apple-ios
  • If you are on M1: cargo build --target aarch64-apple-ios-sim
  • cargo apple open
  • Choose a simulator. I usually choose iPhone 12 (14.4).
  • Press run button.

Custom Protocols

Android

Same as others.

TODO: add how does its scheme actually looks like.

iOS

Same as macOS.

To get the path of your assets, you can call CFBundle::resources_path. So url like wry://assets/index.html could get the html file in assets directory.

IPC

Both support ipc.PostMessage().

Devtools

Set devtools attribute to true when building webview.

Android

Open chrome://inspect/#devices in Chrome to get the devtools window.

iOS

Open Safari > Develop > [Your Device Name] > [Your WebView].

Select a repo