Xamarin.Android：点击通知会导致整个应用程序空白

Question

My Xamarin.Android notification is causing the whole app to go blank when it's clicked. I had the typeof set to a Fragment , which caused the notification to not start my app at all.

Here is the code I'm using to generate my notifications:

        public static int _count = 0;

        public async void SendNotifications()
        {
            await Task.Run(() =>
            {

                var _ctx = Android.App.Application.Context;

                //I've also tried setting the bundle to MainActivity existing bundle with no change
                //Bundle _bundle = MainActivity._bundle;

                var valuesForActivity = new Bundle();
                valuesForActivity.PutInt(MainActivity.COUNT_KEY, _count);
                //I'd eventually like to pass a url string foreach notification but have
                // disabled this line for the sake of simplicity.
                //valuesForActivity.PutString(_main._notificationString, "https://bitchute.com/subscriptions/");

                // When the user clicks the notification, MainActivity will start up.
                // This line works, but it causes the app to go blank
                var resultIntent = new Intent(_ctx, typeof(MainActivity));

                // Pass some values to MainActivity:
                resultIntent.PutExtras(valuesForActivity);

                // Construct a back stack for cross-task navigation:
                var stackBuilder = Android.Support.V4.App.TaskStackBuilder.Create(_ctx);
                //stackBuilder.AddParentStack(Class.FromType(typeof(MainActivity)));
                stackBuilder.AddNextIntent(resultIntent);

                _fm5.GetPendingIntent();

                // Create the PendingIntent with the back stack:
                var resultPendingIntent = stackBuilder.GetPendingIntent(0, (int)Android.App.PendingIntentFlags.UpdateCurrent);

                foreach (var note in ExtNotifications._customNoteList)
                {
                    // Build the notification:
                    var builder = new Android.Support.V4.App.NotificationCompat.Builder(_ctx, MainActivity.CHANNEL_ID)
                                  .SetAutoCancel(true) // Dismiss the notification from the notification area when the user clicks on it
                                  .SetContentIntent(resultPendingIntent) // Start up this activity when the user clicks the intent.
                                  .SetContentTitle(note._noteType) // Set the title
                                  .SetNumber(_count) // Display the count in the Content Info
                                  .SetSmallIcon(Resource.Drawable.bitchute_notification2) // This is the icon to display
                                  .SetContentText(note._noteText);

                    // Finally, publish the notification:
                    var notificationManager = Android.Support.V4.App.NotificationManagerCompat.From(_ctx);
                    notificationManager.Notify(MainActivity.NOTIFICATION_ID, builder.Build());

                    _count++;
                }
            });
        }                                                

The notification text generates fine from this code:

https://github.com/hexag0d/BitChute_Mobile_Android_BottomNav/blob/CookieShare/Classes/ExtNotifications.cs

What I'd really like to do is load a url in one of my fragments, by passing it into the notification, but the first step is having my app not go blank on notification clicked; can anyone tell me what I did wrong here?

Also, I'm not using firebase; I'm just using the vanilla Android notification API, and would prefer to keep it as simple as possible.

EDIT: I forgot to mention that I've also tried setting android:launchMode="singleInstance" in the app manifest as-well as singleTop and others. That didn't work.

Answer 1

You actually need to init an Activity in your pending intent without creating a different Task thread so your SendNotification method would look like:

void SendNotification(string messageBody)
{
try
{
    var intent = new Intent(this, typeof(MainActivity));
    intent.AddFlags(ActivityFlags.ClearTop);
    var pendingIntent = PendingIntent.GetActivity(this, 0, intent, PendingIntentFlags.OneShot);

    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
        .SetSmallIcon(Resource.Drawable.ic_stat_ic_notification)
        .SetContentTitle("Title")
        .SetContentText(messageBody)
        .SetAutoCancel(true)
        .SetContentIntent(pendingIntent);

    NotificationManagerCompat notificationManager = NotificationManagerCompat.From(this);
    notificationManager.Notify(0, notificationBuilder.Build());
}
catch (Exception ex)
{

}
}

Once you do that you can just call your Fragment from this Activity by using some flag like a bundled boolean

Answer 2

I fixed this issue by handling OnNewIntent inside MainActivity , also changing some of the flags, and way that I built the notification. I unfortunately changed a bunch code for how the notification was built at once, at the same time that I handled OnNewIntent , so I'm not sure if all of these changes are necessary. I do know that handling OnNewIntent was absolutely essential; what I don't know is whether or not changing the parameters for the notification builder was necessary. Here is the full working code:

    //the notification class
    public class CustomNotification
    {
        public string _noteType { get; set; }
        public string _noteText { get; set; }
        public string _noteLink { get; set; }
        public int _noteIndex { get; set; }
    }

    //this has to be in MainActivity
    protected override void OnNewIntent(Intent intent)
    {
        string url = "";

        base.OnNewIntent(intent);

        if (intent != null)
        {
            url = intent.Extras.GetString("URL");
        }

        try
        {
            switch (_viewPager.CurrentItem)
            {
                case 0:
                    _fm1.LoadCustomUrl(url);
                    break;
                case 1:
                    _fm2.LoadCustomUrl(url);
                    break;
                case 2:
                    _fm3.LoadCustomUrl(url);
                    break;
                case 3:
                    _fm4.LoadCustomUrl(url);
                    break;
                case 4:
                    _fm5.LoadCustomUrl(url);
                    break;
            }
        }
        catch
        {

        }

    }

    public void SendNotifications(List<CustomNotification> notificationList)
    {
        try
        {
            var _ctx = Android.App.Application.Context;
            int _noteCount = 0;

            foreach (var note in notificationList)
            {
                var resultIntent = new Intent(_ctx, typeof(MainActivity));
                var valuesForActivity = new Bundle();
                valuesForActivity.PutInt(MainActivity.COUNT_KEY, _count);
                MainActivity._NotificationURLList.Add(note._noteLink);
                valuesForActivity.PutInt("Count", _noteCount);
                valuesForActivity.PutString("URL", note._noteLink);
                resultIntent.PutExtras(valuesForActivity);

                //var resultPendingIntent = PendingIntent.GetActivity(_ctx, 0, resultIntent, PendingIntentFlags.UpdateCurrent);
                //set to unique ID per Leo Zhu - MSFT
                var resultPendingIntent = PendingIntent.GetActivity(_ctx, MainActivity.NOTIFICATION_ID, resultIntent, PendingIntentFlags.UpdateCurrent);

                resultIntent.AddFlags(ActivityFlags.SingleTop);

                var builder = new Android.Support.V4.App.NotificationCompat.Builder(_ctx, MainActivity.CHANNEL_ID)
                              .SetAutoCancel(true) // Dismiss the notification from the notification area when the user clicks on it
                              .SetContentIntent(resultPendingIntent) // Start up this activity when the user clicks the intent.
                              .SetContentTitle(note._noteType) // Set the title
                              .SetNumber(_count) // Display the count in the Content Info
                              //xamarin was all whacked out so I had to set this static int from ctrl + F (resource) in resourcedesigner.cs
                              .SetSmallIcon(2130837590) // This is the icon to display
                              .SetContentText(note._noteText);


                MainActivity.NOTIFICATION_ID++;

                // Finally, publish the notification:
                var notificationManager = Android.Support.V4.App.NotificationManagerCompat.From(_ctx);
                notificationManager.Notify(MainActivity.NOTIFICATION_ID, builder.Build());

                _count++;
                _noteCount++;

                //I think if the notification count gets too high android kills the app?  I set this very high just in case
                if (_count >= 300)
                {
                    _count = 0;
                    return;
                }
            }

        }
        catch
        {

        }
    }