public KupiKartuPage(int eventId)
 {
     InitializeComponent();
     BindingContext    = model = new KupiKartuViewModel();
     model.EventId     = eventId;
     BrKarata.Keyboard = Keyboard.Numeric;
 }
        public FrameKupiKartu()
        {
            this.InitializeComponent();
            DataContext = new KupiKartuViewModel();
            var currentView = SystemNavigationManager.GetForCurrentView();

            currentView.AppViewBackButtonVisibility = AppViewBackButtonVisibility.Visible;
            SystemNavigationManager.GetForCurrentView().BackRequested += ThisPage_BackRequested;
        }