Expo Client

The Expo client app for Android and iOS.

To develop or run Expo experiences on your device, download Expo for Android 4.4+ from the Play Store or for iOS 9+ from the App Store. Click here for instructions to install the app on an iOS simulator or Android emulator.

Click here to view our documentation for developing on Expo.

Introduction

This is the source code for the Expo client app used to view experiences published to the Expo service. Most people will not need to build the Expo clients from source.

If you want to build a standalone app that has a custom icon and name, see our documentation here. You're in the wrong place, you shouldn't need to build the Expo clients from source.

If you need to make native code changes to your Expo project, such as adding custom native modules, we can generate a native project for you. You're in the wrong place, you shouldn't need to build the Expo clients from source.

If you want to build the Expo client apps for some reason, there are a few steps to getting this working:

• Join us on Slack at https://slack.expo.io/. The code base and build process is complicated so please ask us if you get stuck.
• Get the iOS and Android clients building on your machine using the Set Up section below.
• Make your native changes and test. You can still use XDE or exp and the rest of Expo's infrastructure.

Set Up

These instructions are different if you are using Expo's internal monorepo. In that case, read the __internal__ instructions instead.

Please use Node 7 and npm 4. We recommend installing Node using nvm. We support building the clients only on macOS.

• Install the Gulp CLI globally: npm i gulp-cli -g.
• Clone xdl, run npm install in the xdl directory and then run gulp build. Next, run npm link in the xdl directory.
• Run npm install in the js and tools-public directories.
• Run npm link xdl in the tools-public directory.
• If you don't have it yet, install exp, the Expo cli.

Android

• Make sure you have Android Studio 2 and the Android NDK version r10e installed.
• Build and install Android with cd android; ./run.sh; cd ... It might fail the first time. If so just run ./run.sh again.

If you are running on an phone with Android 5 you might have to use ./run.sh installDev19Debug. There is a bug running multidex applications in debug mode on Android 5 devices: https://code.google.com/p/android/issues/detail?id=79826.

iOS

• Make sure you have latest non-beta Xcode installed.
• Install Cocoapods: gem install cocoapods --no-ri --no-rdoc
• Make sure you have a JS packager for the root Expo project already running
• cd tools-public; ./generate-files-ios.sh; cd ..
• cd ios; pod install; cd ..
• Run ios/Exponent.xcworkspace in Xcode.

Note: If you have the Expo client app from the Play Store or the App Store you will have to uninstall those before installing this client.

Standalone Apps

If you don't need custom native code outside of the Expo SDK, head over to our documentation on building standalone apps without needing Android Studio and Xcode.

If you're still here, make sure to follow the Configure app.json section of the docs before continuing. You'll need to add the appropriate fields to your app.json before the standalone app scripts can run. Once that's done, continue on to the platform-specific instructions.

Android

The Android standalone app script creates a new directory android-shell-app with the modified Android project in it. It then compiles that new directory giving you a signed or unsigned .apk depending on whether you provide a keystore and the necessary passwords. If there are issues with the app you can open the android-shell-app project in Android Studio to debug.

Here are the steps to build a standalone Android app:

• Publish your experience from XDE or exp. Note the published url.
• cd tools-public.
• If you want a signed .apk, run gulp android-shell-app --url [the published experience url] --sdkVersion [sdk version of your experience] --keystore [path to keystore] --alias [keystore alias] --keystorePassword [keystore password] --keyPassword [key password].
• If you don't want a signed .apk, run gulp android-shell-app --url [the published experience url] --sdkVersion [sdk version of your experience].
• The .apk file will be at /tmp/shell-signed.apk for a signed .apk or at /tmp/shell-debug.apk for an unsigned .apk.
• adb install the .apk file to test it.
• Upload to the Play Store!

iOS

The iOS standalone app script has two actions, build and configure. build creates an archive or a simulator build of the Expo iOS workspace. configure accepts a path to an existing archive and modifies all its configuration files so that it will run as a standalone Expo experience rather than as the Expo client app.

Here are the steps to build a standalone iOS app:

• Publish your experience from XDE or exp. Note the published url.
• cd tools-public.
• gulp ios-shell-app --action build --type [simulator or archive] --configuration [Debug or Release]
• The resulting archive will be created at ../shellAppBase-[type].
• gulp ios-shell-app --url [the published experience url] --action configure --type [simulator or archive] --archivePath [path to Exponent.app] --sdkVersion [sdk version of your experience] --output your-app.tar.gz
• This bundle is not signed and cannot be submitted to iTunes Connect as-is; you'll need to manually sign it if you'd like to submit it to Apple. Fastlane is a good option for this. Also, Expo will do this for you if you don't need to build this project from source.
• If you created a simulator build in the first step, unpack the tar.gz using tar -xvzf your-app.tar.gz. Then you can run this on iPhone Simulator using xcrun simctl install booted <app path> and xcrun simctl launch booted <app identifier>. Another alternative which some people prefer is to install the ios-sim tool and then use ios-sim launch <app path>.
• There are a few more optional flags you can pass to this script. They are all documented in the block comment for createIOSShellAppAsync() inside ios-shell-app.js.

Modifying JS Code

The Expo client apps run a root Expo project in addition to native code. By default this will use a published version of the project, so any changes made in the js directory will not show up without some extra work.

Serve this project locally by running exp start from the js directory. The native Android Studio and XCode projects have a build hook which will find this if exp start is running. Keep this running and rebuild the app on each platform.

Project Layout

• android contains the Android project.
• ios contains the iOS project.
• ios/Exponent.xcworkspace is the Xcode workspace. Always open this instead of Exponent.xcodeproj because the workspace also loads the CocoaPods dependencies.
• js contains the JavaScript source code of the app.
• tools-public contains build and configuration tools.
• template-files contains templates for files that require private keys. They are populated using the keys in template-files/keys.json.
• template-files/ios/dependencies.json specifies the CocoaPods dependencies of the app.

Contributing

Please check with us before putting work into a Pull Request! It is often harder to maintain code than it is to write it. The best place to talk to us is on Slack at https://slack.expo.io.

License

The Expo source code is made available under the BSD 3-clause license. Some of the dependencies are licensed differently, with the MIT license, for example.