Flutter detect killing off the app

Question

I would like to know whether detect killing off the app is possible or not. Let’s say in a chat app, I was able to get timestamp when user leaves the chat room by using onWillPop. But if user killed off the app directly from the chat room, it won’t be fired off. So is there a way to detect that?
Or any suggestions to get timestamp different way?

Answer 1

See also https://flutter.io/flutter-for-android/#how-do-i-listen-to-android-activity-lifecycle-events

You can listen for inactive, paused, and detached. This might be a bit too early but usually it's better to do some cleanup a bit too early and too often than not at all:

WidgetsBinding.instance.addObserver(LifecycleEventHandler(     detachedCallBack: () async => widget.appController.persistState(),     resumeCallBack: () async {       _log.finest('resume...');     })); 

class LifecycleEventHandler extends WidgetsBindingObserver {   LifecycleEventHandler({this.resumeCallBack, this.detachedCallBack});    final FutureVoidCallback resumeCallBack;   final FutureVoidCallback detachedCallBack;  //  @override //  Future<bool> didPopRoute()  //  @override //  void didHaveMemoryPressure()    @override   Future<void> didChangeAppLifecycleState(AppLifecycleState state) async {     switch (state) {       case AppLifecycleState.inactive:       case AppLifecycleState.paused:       case AppLifecycleState.detached:         await detachedCallBack();         break;       case AppLifecycleState.resumed:         await resumeCallBack();         break;     }     _log.finest(''' =============================================================                $state ============================================================= ''');   }  //  @override //  void didChangeLocale(Locale locale)  //  @override //  void didChangeTextScaleFactor()  //  @override //  void didChangeMetrics();  //  @override //  Future<bool> didPushRoute(String route) } 

Edit

With this pull request on 4th November 2019, the enum AppLifecycleState.suspending was renamed to AppLifecycleState.detached. If you are using Flutter with a version prior to 1.12, you must still use AppLifecycleState.suspending.