Scheduling tasks

Some tasks need to be performed at a particular time in the future, some may even be required to recur.

How to do it...

We can schedule tasks for the future using the AlarmManager instance:

1. As scheduling tasks involves running code when the app is closed by the user, we have to get permission to do this:

   [assembly: UsesPermission(Manifest.Permission.SetAlarm)]

2. Then, we need a broadcast receiver that will receive a notification when the alarm is triggered:

   [BroadcastReceiver]
   [IntentFilter(new[] { "xamarincookbook.Alarm" })]
   public class AlarmReceiver : BroadcastReceiver {
     public override void OnReceive(
     Context context, Intent intent) {
       // alarm has triggered
     }
   }

3. When we want to schedule a task, we set an alarm for a specific time and then provide an intent that should be broadcast when the time expires:

   var ringTime = JavaSystem.CurrentTimeMillis() + (long)TimeSpan.FromSeconds(5).TotalMilliseconds;
   var intent = new Intent("xamarincookbook.Alarm");
   var alarm = PendingIntent...