c#

 
 
  public DispatcherTimer _timer;
        public GeneralWindowViewModel()
        {
            _timer = new DispatcherTimer(DispatcherPriority.Render);
            _timer.Interval = TimeSpan.FromSeconds(15);
            _timer.Tick += new EventHandler(timer1_Tick);
            _timer.Start();
            }
            
            public void timer1_Tick(object sender, EventArgs e)
        {
            MessengerInstance.Send<NotificationMessage>(new NotificationMessage("fingerprintTimer"));
            MessengerInstance.Send<NotificationMessage>(new NotificationMessage("RebootFriends"));
        }
 
 
 
 
 MessengerInstance.Register<NotificationMessage>(this, (message) =>
            {  // Checks the actual content of the message.
                switch (message.Notification)
                {
                    case "fingerprintTimer":
                        au = AuthSingleton.Instance.getAuthUser();
                        friends.Clear();
                        auxCheckins.Clear();
                        Friends.Clear();
                        loadFriends();
                        break;
                    default:
                        break;
                }
            });