CODEWITHSUNDEEP
c#xamarin.forms
dotnetdevcsharp
dotnetdevcsharp

Reputation: 3980

Subscribing to notifications interfaces causing crash of application Xamarin Forms Driod

I am following the guide here however when I attempt to launch the notification in Xamarin forms Andriod, I get the following.

https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/local-notifications

INotificationManager notificationManager;
int notificationNumber = 0;


notificationManager = DependencyService.Get<INotificationManager>();
notificationManager.NotificationReceived += (sender, eventArgs) =>
{
  var evtData = (NotificationEventArgs)eventArgs;
  ShowNotification(evtData.Title, evtData.Message);
};

void ShowNotification(string title, string message)
{
    Device.BeginInvokeOnMainThread(() =>
    {
        var msg = new Label()
        {
            Text = $"Notification Received:\nTitle: {title}\nMessage: {message}"
        };
        stacklayout.Children.Add(msg);
    });
}

My Main Activity

[Activity(Label = "THEHOCKEYLAB", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize, LaunchMode = LaunchMode.SingleTop )]
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);


         Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
        

        LoadApplication(new App());
        CreateNotificationFromIntent(Intent);

        Window.SetStatusBarColor(Android.Graphics.Color.Black); //here

    }
    protected override void OnNewIntent(Intent intent)
    {
        CreateNotificationFromIntent(intent);
    }

    void CreateNotificationFromIntent(Intent intent)
    {
        if (intent?.Extras != null)
        {
            string title = intent.GetStringExtra(AndroidNotificationManager.TitleKey);
            string message = intent.GetStringExtra(AndroidNotificationManager.MessageKey);
            DependencyService.Get<INotificationManager>().ReceiveNotification(title, message);
        }
    }
    public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
    {
        Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

        base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    }
}

public interface INotificationManager
{
    event EventHandler NotificationReceived;
    void Initialize();
    void SendNotification(string title, string message, DateTime? notifyTime = null);
    void ReceiveNotification(string title, string message);

}

I get the following error.

System.NullReferenceException: 'Object reference not set to an instance of an object.'

But I have had a look and cant find anything on it am using Xamarin forms version 5.0.0.2083

Its on this line am recieving the error.

notificationManager.NotificationReceived += (sender, eventArgs) =>
{
    var evtData = (NotificationEventArgs)eventArgs;
    ShowNotification(evtData.Title, evtData.Message);
};

Upvotes: 1

Views: 194

Answers (1)

dotnetdevcsharp
dotnetdevcsharp

Reputation: 3980

Never mind I found my answer Credit to this SO. Like all Dependency's it must be registered or will always be null.

Android notification null pointer exception. This needs to be in ur main activity.cs.

 DependencyService.Register<INotificationManager, AndroidNotificationManager>();

Upvotes: 1

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