onResume() and onPause() for widgets on Flutter

Question

Right now, a widget only has initeState() that gets triggered the very first time a widget is created, and dispose(), which gets triggered when the widget is destroyed. Is t

Answer 1

This is a full example demonstrating how to properly handle things, to test this, press home button and resume the app, you shall see didChangeAppLifecycleState is getting called.

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();

    // add the observer
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    // remove the observer
    WidgetsBinding.instance.removeObserver(this);

    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);

    // These are the callbacks
    switch (state) {
      case AppLifecycleState.resumed:
        // widget is resumed
        break;
      case AppLifecycleState.inactive:
        // widget is inactive
        break;
      case AppLifecycleState.paused:
        // widget is paused
        break;
      case AppLifecycleState.detached:
        // widget is detached
        break;
    }
  }

  @override
  Widget build(BuildContext context) => Scaffold();
}