设置里，标题栏有后退按钮



在win平板，可以有后退键，手机也有

pc可以在标题栏

在OnLaunched

//最后
     Windows.UI.Core.SystemNavigationManager.GetForCurrentView().BackRequested += BackRequested;       Windows.UI.Core.SystemNavigationManager.GetForCurrentView().AppViewBackButtonVisibility = Windows.UI.Core.AppViewBackButtonVisibility.Visible;

BackRequested后退方法