What is the equivalent of Android LiveData in Flutter?

Question

Android's LiveData allows to update the UI when the activity is in an active state. So if a background operation has finished while the activity is paused, the activity won't be notified and thus the app won't crush. Can Flutter perform the same behavior?

Answer 1

You can use WidgetsBindingObserver to listen to the application state.

class AppLifecycleReactor extends StatefulWidget {
  const AppLifecycleReactor({ Key key }) : super(key: key);

  @override
  _AppLifecycleReactorState createState() => new _AppLifecycleReactorState();
}

class _AppLifecycleReactorState extends State<AppLifecycleReactor> with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  AppLifecycleState _notification;

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    setState(() { _notification = state; });
  }

  @override
  Widget build(BuildContext context) {
    return new Text('Last notification: $_notification');
  }
}