在后台 fcm flutter 中处理通知

Question

我快疯了，正在寻找一种方法来显示后台通知。我尝试了各种方法，但都无济于事。我使用 firebase_messaging 7.0.3。我只是在尝试 ios。如果有什么效果，请帮忙

_firebaseMessaging.configure(
    onBackgroundMessage: _firebaseMessagingBackgroundHandler,
    onMessage: (Map<String, dynamic> message) async {
      _showNotification(message);
    },
    onLaunch: (Map<String, dynamic> message) async {
      print("onLaunch: $message");
    },
    onResume: (Map<String, dynamic> message) async {
      print("onResume: $message");
    },
  );

Future<dynamic>_firebaseMessagingBackgroundHandler(Map<String,dynamic> message) {
print("FCM backgroundMessageHandler $message");
_showNotification(message);
return Future<void>.value();}

Future _showNotification(Map<String, dynamic> message) async{
var iOSPlatformChannelSpecifics = new IOSNotificationDetails();
var platformChannelSpecifics = new NotificationDetails(iOS: iOSPlatformChannelSpecifics);
print("INI NOTIF $message");
await _localNotifications.show(
  ++_count,
  message['title'],
  message['body'],
  platformChannelSpecifics,
);

}