.NET MAUI推送通知点击报错、接收限制及Manifest配置问题

问题1：仅应用运行时能收到通知 #

后台状态下，系统托盘会直接处理纯notification类型的消息，不会触发FirebaseMessagingService的OnMessageReceived方法。要实现后台收通知并传递跳转参数，需调整消息结构和代码逻辑。

解决步骤 #

• 发送Firebase消息时，必须包含data字段（可同时保留notification字段），示例Payload：

  {
    "to": "DEVICE_TOKEN",
    "data": {
      "NavigateTo": "/DetailsPage",
      "title": "新通知",
      "body": "您有一条新消息"
    },
    "notification": {
      "title": "新通知",
      "body": "您有一条新消息"
    }
  }
  

• 修改FirebaseService的SendNotification方法，适配Android 12+的PendingIntent标记：

  private void SendNotification(string messageBody, string title, IDictionary<string, string> data)
  {
      var intent = new Intent(this, typeof(MainActivity));
      // 添加SingleTop避免重复创建Activity实例
      intent.AddFlags(ActivityFlags.ClearTop | ActivityFlags.SingleTop);
  
      foreach (var key in data.Keys)
      {
          intent.PutExtra(key, data[key]);
      }
  
      // 适配Android 12+的Immutable标记
      var flags = PendingIntentFlags.OneShot;
      if (OperatingSystem.IsOSPlatformVersionAtLeast("android", 31))
      {
          flags |= PendingIntentFlags.Immutable;
      }
  
      var pendingIntent = PendingIntent.GetActivity(this, MainActivity.NotificationId, intent, flags);
  
      var notificationBuilder = new NotificationCompat.Builder(this, MainActivity.ChannelId)
          .SetContentTitle(title)
          .SetSmallIcon(Resource.Drawable.ic_notification)
          .SetContentText(messageBody)
          .SetChannelId(MainActivity.ChannelId)
          .SetContentIntent(pendingIntent)
          .SetPriority(NotificationCompat.PriorityDefault);
  
      var notificationManager = NotificationManagerCompat.From(this);
      notificationManager.Notify(MainActivity.NotificationId, notificationBuilder.Build());
  }
  

问题2：点击通知跳转时抛出System.InvalidOperationException: 'Window was already created' #

错误原因是导航逻辑触发过早，MAUI的AppShell尚未完成初始化，或操作未在UI线程执行。

解决步骤 #

1. 修改MainActivity，将导航参数暂存到Preferences，延迟到OnResume阶段处理：

   protected override void OnCreate(Bundle? savedInstanceState)
   {
       base.OnCreate(savedInstanceState);
       // 无论Intent是否有参数，都先创建通知渠道
       CreateNotificationChanel();
   
       if (Intent?.Extras != null)
       {
           foreach (var key in Intent.Extras.KeySet() ?? [])
           {
               if (key == "NavigateTo")
               {
                   var page = Intent.Extras.GetString(key);
                   if (!string.IsNullOrEmpty(page))
                   {
                       Preferences.Set("NavigateTo", page);
                   }
               }
           }
       }
   }
   
   protected override void OnResume()
   {
       base.OnResume();
   
       if (Preferences.ContainsKey("NavigateTo"))
       {
           var page = Preferences.Get("NavigateTo", string.Empty);
           Preferences.Remove("NavigateTo");
           if (!string.IsNullOrEmpty(page))
           {
               // 确保在UI线程发送导航消息
               MainThread.BeginInvokeOnMainThread(() =>
               {
                   WeakReferenceMessenger.Default.Send(new PushNotificationReceivedMessage
                   {
                       PageToNavigate = page
                   });
               });
           }
       }
   }
   

2. 修改App类的订阅方法，等待AppShell初始化完成后再执行导航：

   private void SubScribeOnNotificationNavigation()
   {
       WeakReferenceMessenger.Default.Register<PushNotificationReceivedMessage>(this, async (recipient, message) =>
       {
           // 等待AppShell实例就绪
           while (AppShell.Current == null)
           {
               await Task.Delay(100);
           }
           // 在UI线程执行导航操作
           await MainThread.InvokeOnMainThreadAsync(async () =>
           {
               await AppShell.Current.GoToAsync(message.PageToNavigate);
           });
       });
   }
   

问题3：添加默认通知渠道元数据后出现APT2260错误 #

错误原因是AndroidManifest中引用的字符串资源不存在，需手动定义对应资源。

解决步骤 #

1. 在Android项目的Resources/values/strings.xml中添加渠道ID的字符串定义：

   <string name="default_notification_channel_id">MyChanel</string>
   

2. 在AndroidManifest.xml中配置元数据：

   <application ...>
       <meta-data
           android:name="com.google.firebase.messaging.default_notification_channel_id"
           android:value="@string/default_notification_channel_id" />
   </application>
   

内容的提问来源于stack exchange，提问作者Wasyster