FirebaseNotifications.md

Firebase Push Notifications

On Firebase Cloud Messaging there are two types of messages that you can send to clients:

Notification messages - Delivered when the application is in background. These messages trigger the onMessageReceived() callback only when your app is in foreground. Firebase will provide the ui for the notification shown on Android device.

{
   "notification" : 
   {
    "body" : "hello",
    "title": "firebase",
    "sound": "default"
   },
    "registration_ids" : ["eoPr8fUIPns:APA91bEVYODiWaL9a9JidumLRcFjVrEC4iHY80mHSE1e-udmPB32RjMiYL2P2vWTIUgYCJYVOx9SGSN_R4Ksau3vFX4WvkDj4ZstxqmcBhM3K-NMrX8P6U0sdDEqDpr-lD_N5JWBLCoV"]
}

Data messages - Handled by the client app. These messages trigger the onMessageReceived() callback even if your app is in foreground/background/killed. When using this type of message you are the one providing the UI and handling when push notification is received on an Android device.

{
    "data": {
        "message" : "my_custom_value",
        "other_key" : true,
        "body":"test"
     },
     "priority": "high",
     "condition": "'general' in topics"
}

Important:

iOS :

• Data message won't display a notification on your device, should use a notification message for that instead.
• For receiving push notifications on the background on should include content_available = true inside the notification key.

Example:

If application on background receives push notification and display a notification.

{
    "data": {
        "message" : "my_custom_value",
        "other_key" : true,
        "body":"test"
     },
     "notification": {
       "body" : "hello",
       "title": "firebase",
       "sound": "default",
        "content_available" : true
     },
     "priority": "high",
     "condition": "'general' in topics"
}

If application on background receives push notification doesn't display any notification.

{
    "data": {
        "message" : "my_custom_value",
        "other_key" : true,
        "body":"test"
     },
     "notification": {
        "content_available" : true
     },
     "priority": "high",
     "condition": "'general' in topics"
}

If "content_available" : true is not sent then you have to tap on the notification for it to be received on the application.

Android:

• Data messages let's you customize notifications ui while notification messages don't (ui is renderered by firebase)

For more information:

https://firebase.google.com/docs/cloud-messaging/concept-options

https://firebase.google.com/docs/cloud-messaging/http-server-ref

Subscribing/Unsubscribing topics

Firebase provide the ability to group devices by using topics. When you send push notifications to a topic only the devices subscribed to this topic will get the notification.

//Subscribing to single topic
CrossFirebasePushNotification.Current.Subscribe("general");

//Subscribing to multiple topics
CrossFirebasePushNotification.Current.Subscribe(new string[]{"baseball","football"});

//Unsubscribing to single topic
CrossFirebasePushNotification.Current.Unsubscribe("general");

//Unsubscribing from multiple topics
CrossFirebasePushNotification.Current.Unsubscribe(new string[]{"food","music"});

//Unsubscribing from all topics
CrossFirebasePushNotification.Current.UnsubscribeAll();

Note: On iOS you don't need to set the topic as /topics/{topic name} that is already handled internally so topics are set equally as on Android just specify the topic name {topic name}.

Notification Events

OnNotificationReceived

  CrossFirebasePushNotification.Current.OnNotificationReceived += (s,p) =>
  {
 
        System.Diagnostics.Debug.WriteLine("Received");
    
  };

OnNotificationOpened

  
  CrossFirebasePushNotification.Current.OnNotificationOpened += (s,p) =>
  {
                System.Diagnostics.Debug.WriteLine("Opened");
                foreach(var data in p.Data)
                {
                    System.Diagnostics.Debug.WriteLine($"{data.Key} : {data.Value}");
                }
             
 };

Note: This is the event were you will navigate to an specific page/activity/viewcontroller, if needed

OnNotificationAction

  
  CrossFirebasePushNotification.Current.OnNotificationAction += (s,p) =>
  {
                System.Diagnostics.Debug.WriteLine("Action");
           
                if(!string.IsNullOrEmpty(p.Identifier))
                {
                    System.Diagnostics.Debug.WriteLine($"ActionId: {p.Identifier}");
				    foreach(var data in p.Data)
					{
						System.Diagnostics.Debug.WriteLine($"{data.Key} : {data.Value}");
					}

                }
             
 };

OnNotificationDeleted (Android Only)

  CrossFirebasePushNotification.Current.OnNotificationDeleted += (s,p) =>
  {
 
        System.Diagnostics.Debug.WriteLine("Deleted");
    
  };

Push Notification Handler

A push notification handler is the way to provide ui push notification customization(on Android) and events feedback on native platforms by using IPushNotificationHandler interface. The plugin has a default push notification handler implementation and it's the one used by default.

On most common use cases the default implementation might be enough so a custom implementation might not be needed at all.

public interface IPushNotificationHandler
{
        //Method triggered when an error occurs
        void OnError(string error);
        //Method triggered when a notification is opened
        void OnOpened(NotificationResponse response);
        //Method triggered when a notification is received
        void OnReceived(IDictionary<string, string> parameters);
}

An example of a custom handler use is the DefaultPushNotificationHandler which is the plugin default implementation to render the push notification ui when sending data messages and supporting notification actions on Android.

Initialize using a PushHandler on Application class on Android and AppDelegate on iOS:

Application class OnCreate on Android:

    #if DEBUG
      FirebasePushNotificationManager.Initialize(this,new CustomPushHandler(),true);
    #else
      FirebasePushNotificationManager.Initialize(this,new CustomPushHandler(),false);
    #endif

To keep the default push notification handler functionality but make small adjustments or customizations to the notification. You can inherit from DefaultPushNotificationHandler and implement OnBuildNotification method which can be used to e.g. load an image from the web and set it as the 'LargeIcon' of a notification (notificationBuilder.SetLargeIcon) or other modifications to the resulting notification.

Note: If you use a custom push notification handler on Android, you will have full control on the notification arrival, so will be in charge of creating the notification ui for data messages when needed.

AppDelegate FinishLaunching on iOS:

      FirebasePushNotificationManager.Initialize(options,new CustomPushHandler());

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