No notification sound when IOS app is open

[MB]

I have a .NET MAUI 8 App. There is sound with notification when app is close and in background.

Notification is visible but no sound when app is running in IOS. I am testing with my mobile, IOS version is 16.6.1

Following is the code to send the message from web.

Dim notificationMessage As Message
If isAndroid Then
notificationMessage = New Message With {
.Token = deviceToken
}
Else
notificationMessage = New Message With {
.Token = deviceToken,
.Apns = New ApnsConfig With {
.Aps = New Aps With {
.Sound = "Default"
}
}
}
End If

[MB]

I am able to fix the notification sound when app is open using the following code.

void NotificationReceived(object source, FCMNotificationReceivedEventArgs e)
{
#if IOS
SystemSound sound = new SystemSound(1007);
sound.PlaySystemSound();
#endif

}

[MB]

I am able to fix the notification sound when app is open in IOS

[Christopher Phillips]

I ran into this issue while working on one of my projects, and managed to find the fix for it.

The issue stems from a missing flag in the iOS FirebaseCloudMessagingImplementation's WillPresentNotification delegate.
Namely, the completionHandler is missing the UNNotificationPresentationOptions.Sound flag.

A temporary workaround for this can be made by manually overriding the UNUserNotificationCenter delegate.

public class FirebaseDelegate : NSObject, IUNUserNotificationCenterDelegate
{
	private static FirebaseDelegate instance = null;

	public static FirebaseDelegate Instance
	{
		get => instance ??= new();
	}

	FirebaseDelegate(){}

	public void Initialize()
	{
		UNUserNotificationCenter.Current.Delegate = this;
	}

	[Export("userNotificationCenter:willPresentNotification:withCompletionHandler:")]
	public void WillPresentNotification(UNUserNotificationCenter center, UNNotification notification, Action<UNNotificationPresentationOptions> completionHandler)
	{
		var fcmNotification = notification.ToFCMNotification();
		((FirebaseCloudMessagingImplementation)CrossFirebaseCloudMessaging.Current).OnNotificationReceived(fcmNotification);

		if (!fcmNotification.IsSilentInForeground)
		{
			if (OperatingSystem.IsIOSVersionAtLeast(14))
			{
				completionHandler(UNNotificationPresentationOptions.Banner 
					| UNNotificationPresentationOptions.List 
					| UNNotificationPresentationOptions.Sound);

			}
			else
			{
				completionHandler( UNNotificationPresentationOptions.Alert
					| UNNotificationPresentationOptions.Sound);
			}
		}
	}

	[Export("userNotificationCenter:didReceiveNotificationResponse:withCompletionHandler:")]
	public void DidReceiveNotificationResponse(UNUserNotificationCenter center, UNNotificationResponse response, Action completionHandler)
	{
		((FirebaseCloudMessagingImplementation)CrossFirebaseCloudMessaging.Current).DidReceiveNotificationResponse(center, response, completionHandler);
	}
}

And then implement it after your Plugin.Firebase implementation in your MauiProgram.cs

	FirebaseCloudMessagingImplementation.Initialize();
	FirebaseDelegate.Instance.Initialize();

Do note that the payload needs to contain the sound key in the apns payload for this to work:

"message": {
  ...
  "apns": {
    "payload": {
      "aps": {
        "sound" : "default"
      }
    }
  }
}

I will submit a pull request with the proposed fix