我正在使用“AppLifecycleState”推送通知构建Flutter应用(图)

我正在使用 Firebase 推送通知构建一个 Flutter 应用程序。

我希望应用在收到消息时显示带有文本的弹出模式。

“FirebaseMessaging.onBackgroundMessage”函数需要放置在 TOP LEVEL（任何类之外）。那么，当应用程序再次被带到前台时，如何将应用程序在后台时可能收到的消息中的消息数据推送到我的 App Class 以显示消息内容？我正在使用“AppLifecycleState”来检测应用程序何时返回前台，但我无法获取消息数据，因为它是在顶层而不是在类中接收的。

请参阅下面的代码（有关我遇到的问题，请参阅最后几行）…

  //TOP LEVEL-----
  Future _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
    if (message.messageId!="") {
        debugPrint("Have received a background message! Will have to grab the message from here somehow if the user didn't interact with the system tray message link");
    } 
  }
  Future main() async {
       await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
       FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

       runApp(MyApp());
  }
  //APP CLASS-----
  class MyAppextends StatefulWidget {        
       State createState() => _MyAppState();
  }
       
  //APP STATE CLASS
  class _MyAppState extends State  with WidgetsBindingObserver{

       @override  
       void initState() {
          super.initState();
          _initiateNotificationForegroundListener();
          _initiateInteractedMessage();
       }
       // This variable will tell you whether the application is in foreground or not. 
       bool _isInForeground = true;
       //Initiate Foreground Notification Listener (works)

       void _initiateNotificationForegroundListener() {
         FirebaseMessaging.onMessage.listen((RemoteMessage message) {
            _handleNotificationInstruction(message);
         });
       }
       //Initiate Background/Closed Notification Listener if user clicks the message in the system try (works)
       Future _initiateInteractedMessage() async {
            RemoteMessage? message = await FirebaseMessaging.instance.getInitialMessage();
           if (message != null) {     
                _handleNotificationInstruction(message);
           }

           // When app is in background (Stream listener) 
           FirebaseMessaging.onMessageOpenedApp
           .listen(_handleNotificationInstruction);
       }
        void _handleNotificationInstruction(RemoteMessage message) {
           //Create popup to display message info (works)
        }
        //Detect when an app moves in to the foreground
        @override

        void didChangeAppLifecycleState(AppLifecycleState state) {
             super.didChangeAppLifecycleState(state);
             _isInForeground = state == AppLifecycleState.resumed;
             if(_isInForeground){
                     /** HELP!!!
                     /* How can I check what message might have been received while app was in the background?? ie. the top-level _firebaseMessagingBackgroundHandler function??
                     **/
             }
        }