Xamarin Alarmmanager Android

Xamarin AlarmManager Android

The problem is that your BroadcastReceiver does not have the [BroadcastReceiver] attribute.

This code works:

AlarmReceiver.cs

[BroadcastReceiver]
public class AlarmReceiver : BroadcastReceiver
{
    public override void OnReceive(Context context, Intent intent)
    {
        var message = intent.GetStringExtra("message");
        var title = intent.GetStringExtra("title");

        var resultIntent = new Intent(context, typeof(MainActivity));
        resultIntent.SetFlags(ActivityFlags.NewTask | ActivityFlags.ClearTask);

        var pending = PendingIntent.GetActivity(context, 0,
            resultIntent,
            PendingIntentFlags.CancelCurrent);

        var builder =
            new Notification.Builder(context)
                .SetContentTitle(title)
                .SetContentText(message)
                .SetSmallIcon(Resource.Drawable.Icon)
                .SetDefaults(NotificationDefaults.All);

        builder.SetContentIntent(pending);

        var notification = builder.Build();

        var manager = NotificationManager.FromContext(context);
        manager.Notify(1337, notification);
    }
}

MainActivity.cs

[Activity(Label = "App3", MainLauncher = true, Icon = "@drawable/icon")]
public class MainActivity : Activity
{
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        SetContentView(Resource.Layout.Main);

        var button = FindViewById<Button>(Resource.Id.MyButton);

        button.Click += delegate
        {
            var alarmIntent = new Intent(this, typeof(AlarmReceiver));
            alarmIntent.PutExtra("title", "Hello");
            alarmIntent.PutExtra("message", "World!");

            var pending = PendingIntent.GetBroadcast(this, 0, alarmIntent, PendingIntentFlags.UpdateCurrent);

            var alarmManager = GetSystemService(AlarmService).JavaCast<AlarmManager>();
            alarmManager.Set(AlarmType.ElapsedRealtime, SystemClock.ElapsedRealtime() + 5*1000, pending);
        };
    }
}

Starting AlarmManager in Android (C#)

I think the problem is that you didn't successfully declare your MyBroadcastReceiver, in xamarin, we can use:

[BroadcastReceiver(Enabled = true)] 

to declare this broadcast. It's like declare it in traditional android manifest like this:

<receiver android:name="MyBroadcastReceiver" /> 

So, MyBroadcastReceiver should be like this:

[BroadcastReceiver(Enabled = true)]
public class MyBroadcastReceiver : BroadcastReceiver
{
    public override void OnReceive(Context context, Intent intent)
    {
        Toast.MakeText(context, "Time Up... Now Vibrating !!!",
                ToastLength.Long).Show();
        Vibrator vibrator = (Vibrator)context
                .GetSystemService(Context.VibratorService);
        vibrator.Vibrate(2000);
    }
}

Now you can get the toast: "Time Up... Now Vibrating !!!"

Xamarin Android - How to schedule and alarm with a BroadcastReceiver

This is how I'm creating a local notification in my Xamarin app.

DateTime time = ... // whatever time
AlarmManager manager = (AlarmManager)context.GetSystemService(Context.AlarmService);

Java.Util.Calendar calendar = Java.Util.Calendar.Instance;
calendar.TimeInMillis = Java.Lang.JavaSystem.CurrentTimeMillis();

calendar.Set(time.Year, time.Month - 1, time.Day, time.Hour, time.Minute, 0);
manager.SetRepeating(AlarmType.RtcWakeup, calendar.TimeInMillis,
AlarmManager.IntervalDay, pendingIntent);

And here is the BroadcastReceiver class:

[BroadcastReceiver]
public class AlarmReceiver : BroadcastReceiver
{

    public override void OnReceive(Context context, Intent intent)
    {
        NotificationManager nManager = (NotificationManager)context.GetSystemService(Context.NotificationService);

        Intent repeatingIntent;

        // Here I'm opening two different Activities based on condition
        if (CommonUtils.isLoggedIn()))
        {
            repeatingIntent = new Intent(context, typeof(MainActivity));
            repeatingIntent.PutExtra(MainActivity.SELECT_TAB, 1);
        }
        else
        {
            repeatingIntent = new Intent(context, typeof(SplashActivity));
        }

        repeatingIntent.SetFlags(ActivityFlags.ClearTop);

        PendingIntent pIntent = PendingIntent.GetActivity(context, 100, repeatingIntent, PendingIntentFlags.UpdateCurrent);

        NotificationCompat.Builder builder = new NotificationCompat.Builder(context)
            .SetContentIntent(pIntent)
            .SetSmallIcon(Resource.Drawable.az_logo_small)
            .SetColor(ContextCompat.GetColor(context, Resource.Color.PrimaryColor))
            .SetContentTitle(CommonUtils.MAIN_TITLE)
            .SetContentText(UIMessages.VITAL_REMINDER)
            .SetAutoCancel(true);

        nManager.Notify(100, builder.Build());
    }
}

and in AndroidManifest.xml, you need this permission

<uses-permission android:name="com.android.alarm.permission.SET_ALARM" />

also need the register the BroadcastReceiver in AndroidManifest.xml

<application android:label="YourAppName" android:largeHeap="true" android:icon="@drawable/ic_launcher">
    <receiver android:name=".AlarmReceiver"></receiver>
</application>

Hope it helps.

How to set accurate time for Xamarin.Android AlarmManager

If you really need precision try to use the SetExact() method of the alarm manager class.

TimeSpan span = calendarEvent.StartTime - DateTime.Now;
manager.SetExact(AlarmType.ElapsedRealtime,(long)(SystemClock.ElapsedRealtime() + span.TotalMilliseconds),pendingIntent);

And I don't know if it is relevant, but if you are using events for a calendar maybe you should use RTC, since AlarmType.RTC is based on the clock, whereas AlarmType.ElapsedRealTime is based on the time passed since the device was turned on.

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