samples/add_to_app

Add-to-App Sample

This directory contains a bunch of Android and iOS projects that each import a standalone Flutter module.

Goals for this sample

• Show developers how to add Flutter to their existing applications.
• Show the following options:
  • Whether to build the Flutter module from source each time the app builds or rely on a separately pre-built module.
  • Whether plugins are needed by the Flutter module used in the app.

Installing Cocoapods

The iOS samples in this repo require the latest version of Cocoapods. To install it, run the following command on a MacOS machine:

sudo gem install cocoapods

See https://guides.cocoapods.org/using/getting-started.html for more details.

The important bits

Flutter modules

There are two Flutter modules included in the codebase:

• flutter_module displays the dimensions of the screen, a button that increments a simple counter, and an optional exit button.
• flutter_module_using_plugin does everything flutter_module does and adds another button that will open the Flutter documentation in a browser using the url_launcher Flutter plugin.

Before using them, you need to resolve the Flutter modules' dependencies. Do so by running this command from within the flutter_module and flutter_module_using_plugin directories:

flutter packages get

Android and iOS applications

In addition to the Flutter modules, this repo also includes a number of Android and iOS applications that demonstrate different ways of importing them.

With the exception of android_using_prebuilt_module, the Android apps are ready to run once you've completed the flutter packages get commands listed above. Two of the iOS apps (ios_fullscreen and ios_using_plugin) use Cocoapods, though, so you need to run this command within their project directories to install their dependencies:

pod install

Once that command is complete, you'll find an xcworkspace file in the project directories with the correct Flutter module (and any other dependencies) included. Open that workspace file, and the app is ready to build and run.

android_fullscreen and ios_fullscreen

These apps showcase a relatively straightforward integration of flutter_module:

• The Flutter module is built along with the app when the app is built.
• The Flutter engine is warmed up at app launch.
• The Flutter view is presented with a full-screen Activity or UIViewController.
• The Flutter view is a navigational leaf node; it does not launch any new, native Activities or UIViewControllers in response to user actions.

If you are new to Flutter's add-to-app APIs, these projects are a great place to begin learning how to use them.

android_using_plugin and ios_plugin

These apps are similar to android_fullscreen and ios_fullscreen, with the following differences:

• Rather than importing flutter_module, they import flutter_module_using_plugin.
• They include the native code (Kotlin or Swift) required to initialize plugins at Flutter engine creation time.
• Their Flutter view includes an additional button that opens the Flutter docs in the mobile device's browser.

If you're interested in learning what additional steps an app needs to take in order to use a Flutter module that relies on plugins, these projects can help.

android_using_prebuilt_module and ios_using_prebuilt_module

These apps are essentially identical to android_fullscreen and ios_fullscreen, respectively, with one key difference. Rather than being set up to compile the flutter_module from source each time the app is built, they import a the module as a prebuilt aar (Android) or framework (iOS). This can be useful for teams that don't want to require every developer working on the app to have the Flutter toolchain installed on their local machines.

Prior to building either project for the first time, the flutter_module needs to be built.

Building for android_using_prebuilt_module

To build flutter_module as an aar, run this command from the flutter_module directory:

flutter build aar

It will produce aar files for debug, profile, and release mode. The Android app is configured to import the appropriate aar based on its own build configuration, so if you build a debug version of the app, it will look for the debug aar, and so on.

If the flutter_module project is updated, the aar files must be rebuilt via one of the commands above in order for those changes to appear in the app.

Building for ios_using_prebuilt_module

To build flutter_module as a set of frameworks, run this command from the flutter_module directory:

flutter build ios-framework --output=../ios_using_prebuilt_module/Flutter

This will output frameworks for debug, profile, and release modes into ios_using_prebuilt_module/Flutter. The project file for ios_using_prebuilt_module has been configured to find the frameworks there.

For more information on how to modify an existing iOS app to reference prebuilt Flutter frameworks, see this article in the Flutter GitHub wiki:

https://flutter.dev/docs/development/add-to-app/ios/project-setup

Questions/issues

If you have a general question about incorporating Flutter into an existing iOS or Android app, the best places to go are:

• The FlutterDev Google Group
• The Flutter Gitter channel
• StackOverflow

If you run into an issue with the sample itself, please file an issue in the main Flutter repo.