title: Notification click in Android(Xamarin Forms)
body: <p>I used Xamarin Form. I have an application with notifications that open a certain activity if I click them. I want that, if I click the notification and the activity is already opened, it's not started again, but just brought to front.
  It is my code for notification:</p>
  
  <pre><code>public void Show(string title, string body, int id, DateTime notifyTime)
  {
      var intent = CreateIntent(id);
  
      var localNotification = new LocalNotification();
      localNotification.Title = title;
      localNotification.Body = body;
      localNotification.Id = id;
      localNotification.NotifyTime = notifyTime;
      if (NotificationIconId != 0)
      {
          localNotification.IconId = NotificationIconId;
      }
      else
      {
          localNotification.IconId = Resource.Drawable.Icon24;
      }
  
      var serializedNotification = SerializeNotification(localNotification);
      intent.PutExtra(ScheduledAlarmHandler.LocalNotificationKey, serializedNotification);
  
      var pendingIntent = PendingIntent.GetBroadcast(Application.Context, 0, intent, PendingIntentFlags.CancelCurrent);
      var triggerTime = NotifyTimeInMilliseconds(localNotification.NotifyTime);
      var alarmManager = GetAlarmManager();
  
      alarmManager.Set(AlarmType.RtcWakeup, triggerTime, pendingIntent);
  }
  </code></pre>
  
  <p>It is code in ScheduledAlarmHandler:</p>
  
  <pre><code> [BroadcastReceiver(Enabled = true)]
  public class ScheduledAlarmHandler : BroadcastReceiver
  {
  ...........
  public override void OnReceive(Context context, Intent intent)
  {
      var extra = intent.GetStringExtra(LocalNotificationKey);
      var notification = DeserializeNotification(extra);
  
      var builder = new NotificationCompat.Builder(Application.Context)
          .SetContentTitle(notification.Title)
          .SetContentText(notification.Body)
          .SetSmallIcon(notification.IconId)
          .SetSound(RingtoneManager.GetDefaultUri(RingtoneType.Notification))
          .SetAutoCancel(true);
  
      var resultIntent = LocalNotificationsService.GetLauncherActivity();
      resultIntent.SetFlags(ActivityFlags.NewTask | ActivityFlags.ClearTask);
      var stackBuilder = Android.Support.V4.App.TaskStackBuilder.Create(Application.Context);
      stackBuilder.AddNextIntent(resultIntent);
      var resultPendingIntent =
          stackBuilder.GetPendingIntent(0, (int)PendingIntentFlags.UpdateCurrent);
      builder.SetContentIntent(resultPendingIntent);
  
      var notificationManager = NotificationManagerCompat.From(Application.Context);
      notificationManager.Notify(notification.Id, builder.Build());
  }
  ....
  }
  </code></pre>
  
  <p>This is atribute for my MainActivity</p>
  
  <pre><code>[Activity (Icon = "@drawable/icon", 
  ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation,      LaunchMode.SingleTop)]
  </code></pre>