To leverage Flutter debugging functionality 
  such as hot reload, see  Debugging your add-to-app module.

Using Flutter increases your app size.

Option A - Embed with CocoaPods and the Flutter SDK

This method requires every developer working on your
project to have a locally installed version of the Flutter SDK.
The Flutter module is compiled from source each time the app is built.
Simply build your application in Xcode to automatically
run the script to embed your Dart and plugin code.
This allows rapid iteration with the most up-to-date
version of your Flutter module without running additional
commands outside of Xcode.

The following example assumes that your existing
application and the Flutter module are in sibling
directories. If you have a different directory structure,
you may need to adjust the relative paths.