未处理的异常:NoSuchMethodError:在空调用方法"toRawHandle" [英] Unhandled Exception: NoSuchMethodError: The method 'toRawHandle' was called on null
问题描述
我在我的Flutter应用程序中将 firebase_messaging 库用于Firebase推送通知.
i am using firebase_messaging library in My Flutter Application for Firebase Push Notifications.
当前，我的firebase_messaging版本是 firebase_messaging:^ 5.1.5 ，该版本最近更新为最新版本.
Currently my firebase_messaging version is firebase_messaging: ^5.1.5 which was recently updated an the latest one.
我正在尝试在后台以及终止应用程序时接收通知.
i am trying to receive notification in background as well as when application is terminated.
我已按照firebase_messaging文档中提到的所有步骤进行操作，但不幸的是，我在抖动中遇到了上述错误.
i have followed all the steps as mentioned in the documentation of firebase_messaging but unfortunately i am getting the above error in flutter.
这是我在dart中的通知处理程序类
this is my notification handler class in dart
notification_handler.dart
import 'dart:async';
import 'dart:io';
import 'dart:math';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:path_provider/path_provider.dart';
import 'package:http/http.dart' as http;
class NotificationHandler {
FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;
FirebaseMessaging _fcm = FirebaseMessaging();
StreamSubscription iosSubscription;
static final NotificationHandler _singleton =
new NotificationHandler._internal();
factory NotificationHandler() {
return _singleton;
}
NotificationHandler._internal();
Future<dynamic> myBackgroundMessageHandler(
Map<String, dynamic> message) async {
print("onLaunch: $message");
_showBigPictureNotification(message);
// Or do other work.
}
initializeFcmNotification() async {
flutterLocalNotificationsPlugin = new FlutterLocalNotificationsPlugin();
var initializationSettingsAndroid =
new AndroidInitializationSettings('ic_launcher');
var initializationSettingsIOS = new IOSInitializationSettings(
onDidReceiveLocalNotification: onDidReceiveLocalNotification);
var initializationSettings = new InitializationSettings(
initializationSettingsAndroid, initializationSettingsIOS);
flutterLocalNotificationsPlugin.initialize(initializationSettings,
onSelectNotification: onSelectNotification);
if (Platform.isIOS) {
iosSubscription = _fcm.onIosSettingsRegistered.listen((data) {
// save the token OR subscribe to a topic here
});
_fcm.requestNotificationPermissions(IosNotificationSettings());
} else {
_saveDeviceToken();
}
_fcm.configure(
onMessage: (Map<String, dynamic> message) async {
print("onMessage: $message");
_showBigPictureNotification(message);
},
onBackgroundMessage: myBackgroundMessageHandler,
onLaunch: (Map<String, dynamic> message) async {
print("onLaunch: $message");
},
onResume: (Map<String, dynamic> message) async {
print("onResume: $message");
},
);
}
/// Get the token, save it to the database for current user
_saveDeviceToken() async {
String fcmToken = await _fcm.getToken();
print("FCM_TOKEN: $fcmToken");
}
Future<void> _showBigPictureNotification(message) async {
var rng = new Random();
var notifId = rng.nextInt(100);
var largeIconPath = await _downloadAndSaveImage(
'https://cdn.pixabay.com/photo/2019/04/21/21/29/pattern-4145023_960_720.jpg',
'largeIcon');
var bigPicturePath = await _downloadAndSaveImage(
'https://cdn.pixabay.com/photo/2019/04/21/21/29/pattern-4145023_960_720.jpg',
'bigPicture');
var bigPictureStyleInformation = BigPictureStyleInformation(
bigPicturePath, BitmapSource.FilePath,
largeIcon: largeIconPath,
largeIconBitmapSource: BitmapSource.FilePath,
contentTitle: message['data']['title'],
htmlFormatContentTitle: true,
summaryText: message['data']['body'],
htmlFormatSummaryText: true);
var androidPlatformChannelSpecifics = AndroidNotificationDetails(
'12', 'trading_id', message['data']['body'],
importance: Importance.High,
priority: Priority.High,
style: AndroidNotificationStyle.BigPicture,
styleInformation: bigPictureStyleInformation);
var platformChannelSpecifics =
NotificationDetails(androidPlatformChannelSpecifics, null);
await flutterLocalNotificationsPlugin.show(
notifId,
message['data']['title'],
message['data']['body'],
platformChannelSpecifics,
payload: message['data']['body']);
}
Future<void> _showBigTextNotification(message) async {
var rng = new Random();
var notifId = rng.nextInt(100);
var bigTextStyleInformation = BigTextStyleInformation(
message['data']['body'],
htmlFormatBigText: true,
contentTitle: message['data']['title'],
htmlFormatContentTitle: true,
summaryText: message['data']['body'],
htmlFormatSummaryText: true);
var androidPlatformChannelSpecifics = AndroidNotificationDetails(
'12', 'trading_id', '',
importance: Importance.High,
priority: Priority.High,
style: AndroidNotificationStyle.BigText,
styleInformation: bigTextStyleInformation);
var platformChannelSpecifics =
NotificationDetails(androidPlatformChannelSpecifics, null);
await flutterLocalNotificationsPlugin.show(
notifId,
message['data']['title'],
message['data']['body'],
platformChannelSpecifics,
payload: message['data']['body']);
}
Future onSelectNotification(String payload) async {
if (payload != null) {
debugPrint('notification payload: ' + payload);
}
// await Navigator.push(
// context,
// new MaterialPageRoute(builder: (context) => new SecondScreen(payload)),
// );
}
Future<void> onDidReceiveLocalNotification(
int id, String title, String body, String payload) async {
// display a dialog with the notification details, tap ok to go to another page
}
Future<String> _downloadAndSaveImage(String url, String fileName) async {
var directory = await getApplicationDocumentsDirectory();
var filePath = '${directory.path}/$fileName';
var response = await http.get(url);
var file = File(filePath);
await file.writeAsBytes(response.bodyBytes);
return filePath;
}
}
并且我已经在主屏幕中这样称呼了它
and i have called it like this in my home screen
@override
void initState() {
// TODO: implement initState
super.initState();
new NotificationHandler().initializeFcmNotification();
}
推荐答案
在浏览了几个git线程和stackoverflow线程后，我终于找到了最短的答案，没人能告诉我们:
After surfing for several git threads and stackoverflow threads, I finally found the shortest answer that no one could tell:
只是将手放在全球范围内"
"JUST PUT THE HANDLERS IN GLOBAL SCOPE"
在您的what.dart文件中，只需将_firebaseMessaging和4个处理程序，onMessage，onLaunch等...放置在本地类之外，然后就可以了！没有崩溃！
in your whatever.dart file, just put the _firebaseMessaging and the 4 handlers, onMessage, onLaunch, etc... outside local class, and VOILA!! NO CRASH!
原始:
I used bkmza answer , but was not OP fix for crossplatform
出于某些原因，设置
void initState() {
super.initState();
_firebaseMessaging.configure
}
无法正常工作，然后我尝试了
was not working, then I tried
Future.delayed(Duration(seconds: 1), () {
_firebaseMessaging.configure
}
);
我可以完美地工作了:)
And I got it working flawlessly :)
也许FCM初始化尚未准备好配置处理程序，在Firebase Core完全加载使其正常工作之后设置了延迟
Maybe FCM initialisations was not ready to configure handlers, setting a delay after Firebase Core fully load made it work properly
这篇关于未处理的异常:NoSuchMethodError:在空调用方法"toRawHandle"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
