Background Handler communication (Android)

[kevinarch]

Hi, i'm developing a VoIP app and having problem with background handler. What i want is: sending push with type "call" then the app will show Call UI, later if receive push type "hangup" , the app will close that call UI.

In background handler i'm using a singleton global class to inform hang up event with a StreamController and CallScreen widget will listen to that stream to close itself.

Then i found out that flutterfire will start another isolate for background handler (turn off device) , so it will create another singleton class -> i can't close my CallScreen UI with this new singleton class.

Is it possible to do something like this with flutterfire's background isolate ?

Example pseudo code:

class SingletonGlobal {
  /// singleton class

  final hangUpStreamController = StreamController<HangUpEvent>.broadcast();

  void addHangupEvent(HangUpEvent event) {
    hangUpStreamController.add(event);
  }
}

class CallScreen extends StatefulWidget {
  //// ...
    @override
    void initState() {
      SingletonGlobal().hangUpStreamController.stream.listen((event) => closeCallUI(event));
    }
}

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp();
  await appInit();

  if (message.data.type = 'hangup') {
    SingletonGlobal().addHangupEvent(hangUpEvent);
}