BeFriend.Views.FirstPageView.OnNavigatedTo C# (CSharp) Метод

        protected override void OnNavigatedTo(NavigationEventArgs ex)
        {
            SystemNavigationManager.GetForCurrentView().AppViewBackButtonVisibility = AppViewBackButtonVisibility.Visible;
            SystemNavigationManager.GetForCurrentView().BackRequested += (s, e) =>
            {
                Frame.Navigate(typeof(MainPage));
            };
        }