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

            mapView = new NMapView(View.Frame)
            {
                //set the delegate for map view
                WeakDelegate = this
            };
            // set the application api key for Open MapViewer Library
            mapView.SetClientId(AppSetting.CLIENT_ID);
            mapView.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight;
            View.InsertSubview(mapView, 0);

            // set min and max level for range in the UIStepper
            InitStepper(mapView.MaxZoomLevel(), mapView.MinZoomLevel(), 11);
            View.BringSubviewToFront(levelSetpper);

            mapView.SetBuiltInAppControl(true);
            mapView.Layer.AddAnimation(new Animation(this), "mapViewAnimation");
        }