public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            // Perform any additional setup after loading the view, typically from a nib.
            btnStart.Enabled = true;
            btnStop.Enabled  = false;
            //btnReset.Enabled = true;

            btnStart.TouchUpInside += delegate {
                btnStart.Enabled = false;
                btnStop.Enabled  = true;
                timer            = NSTimer.CreateRepeatingScheduledTimer(TimeSpan.FromSeconds(1), timer_tick);
            };

            btnStop.TouchUpInside += delegate {
                btnStart.Enabled = true;
                btnStop.Enabled  = false;
                timer.Invalidate();
            };

            btnReset.TouchUpInside += delegate {
                MyTimerLogic.Rest();
                lblDisplay.Text  = MyTimerLogic.GetCurrentTickCount();
                btnStart.Enabled = true;
                btnStop.Enabled  = false;
            };
        }