Launching app from notification

[jkuek]

I couldn't find where this is covered, but how do I handle the case where the user taps on a notification to launch the app? (for both iOS and Android)

I want to retrieve the notification details so that I can navigate my webview to the correct URL.

I tried this:

    public class MainActivity : MauiAppCompatActivity
    {
        protected override void OnNewIntent(Intent? intent)
        {
            base.OnNewIntent(intent);
            IFirebasePushNotification.Current.ProcessIntent(this, intent);
        }
    }

But it doesn't appear to work.

I'm using MAUI .NET 9 with Plugin.FirebasePushNotifications 3.1.20-pre

[jkuek]

Looking at the example project, the notification includes the click_action and category keys, and then there's an IntentFilter in MainActivity.cs:

[IntentFilter(new[] { "medication_intake" }, Categories = new[] { "android.intent.category.DEFAULT" })]

Is this the "proper" way to handle app launch from a notification tap?

Unfortunately I haven't been able to run the demo project yet, so I'm just relying on code inspection.

For my use-case, I only need one behaviour: when the user clicks on a notification, the app should navigate to a specific URL (using an eventId key from the notification).

Do I still need to include the click_action in my notification? How can I add a catch-all for every time the user taps on a notification?

[jkuek]

Ok, which version of the library do you use? I remember there was an issue with one version of the library concerning something like this. Also, what is the LaunchMode you use on your MainActivity in Android?

My launchMode is currently LaunchMode.SingleTop

I'm on 3.1.20-pre (I was previously on 3.0.28, but upgraded after reading it might resolve some of the other issues I'm having, e.g. notifications not showing when the app is in foreground)

I can work around this issue by manually parsing Intent.Extras in OnCreate() and handling it, but from what I have read this shouldn't be required?

By the way, I have got the sample project running: I ended up needing to remove the project reference to Plugin.FirebasePushNotifications and using the (prerelease) Nuget package instead, as I didn't have the .NET7.0 framework installed.

[thomasgalliker]

Do you have a specific reason why you use SingleTop? I'd highly recommend to use LaunchMode.SingleTask. SingleTop prevents multiple instances only if the activity is already at the top. Otherwise, it creates a new one. This is probably (?) not what you want.

[jkuek]

SingleTop was just the default from my new MAUI app. I have switched to SingleTask, which has solved some of the auxiliary issues (e.g. notification not always received if app is closed), but the issue of no NotificationOpened when opening a notification after closing the app still remains.

The good news is the sample app does appear to work: when I launch the app from the notification then shows the NotificationOpened dialog. So whatever the issue is, it's likely outside of the Plugin.FirebasePushNotifications library. I'm trying to go through the configuration now to see what is different between the sample app and my own.

[thomasgalliker]

I'd be very interested what finally caused the issue, so I can update the readme with more infos regarding setup. (I just added the LaunchMode.SingleTask to the readme too).

More things to check:

• Do you create a default notification channel (in Android only)? If the app is killed, I need to have at least one notification channel in order to present the notification popup.
• Did you check the log debug output if anything regarding FirebasePushNotificationManager or similar is logged? (the plugin logs a lot of important messages to ILogger... it pays off the setup Microsoft.Extensions.Logging in your app, especially file-based logging, so you can check the log files once you killed the app and the debugger).
• What notification message do you send to the app? This can be very crucial. If something is missing, it might not be handled the correct way. Just post a simplified json message here (remove sensitive data).

[jkuek]

I'm not ruling out the notification format being incorrect, but the backend creating the message has been used for previous (Xamarin) applications. The full FCM message as sent to Google is not being logged, but I can get a sanitized sample JSON if necessary.

I do get NotificationOpened if app is in background and NotificationReceived if app is in foreground. It's only when the app is "closed" and then launched from the notification that it doesn't work. And this problem doesn't occur in the sample app, only in mine...

This makes me think the issue is not with the format of the notification, but rather in my app config or init. For example, if NotificationReceived is not subscribed early enough when the app launches.

Much of my implementation is actually close to your sample project, given I was already using MVVM. I only set up one notification channel:

                    o.Android.NotificationChannels = [new NotificationChannelRequest() {  
                        ChannelId = "FirebasePushNotificationChannel", 
                        ChannelName = "general",
                        IsDefault = true,
                        LockscreenVisibility = NotificationVisibility.Public,
	                    Importance = NotificationImportance.High, 
                    }];

I am using Serilog in my app but haven't configured logging to file yet.

It probably comes down to a process of elimination now, given I have one working app and one not.

[jkuek]

OK, the root cause was because this this line in UseFirebasePushNotifications() was commented :
o.QueueFactory = new PersistentQueueFactory();

Without that line, tapping on a notification to launch the app does not result in a NotificationOpened event. Once the line is added, the event occurs.

I am assuming this meant that the notifications were being correctly trapped and parsed by the library, but ultimately the notification is not queued and hence not handled.

I must have commented that out while trying to identify crashing on iOS a couple of weeks ago

[thomasgalliker]

Btw, I changed the default QueueFactory to be the InMemoryQueueFactory in the latest pre-release. Of course you can also use PersistentQueueFactory but at least for those who don't specify the o.QueueFactory explicitly, there is be a simple memory-basaed queue used now.

[jkuek]

Does this impact launching app from a notification? I'm assuming the PersistentQueueFactory just retains the pending notifications when the app is terminated, whereas InMemoryQueueFactory doesn't but what is the practical change?