onResume() and onPause() for widgets on Flutter

There is an abstract class caller WidgetsBindingObserver

https://docs.flutter.io/flutter/widgets/WidgetsBindingObserver-class.html

in

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

there is the “state”, can be manage as

switch(state) {
  case AppLifecycleState.resumed:
    // Handle this case
    break;
  case AppLifecycleState.inactive:
    // Handle this case
    break;
  case AppLifecycleState.paused:
    // Handle this case
    break;
  case AppLifecycleState.suspending:
    // Handle this case
    break;
}