uwp戻るボタン

uwp.md

SystemNavigationManager.GetForCurrentView().AppViewBackButtonVisibility = AppViewBackButtonVisibility.Visible; ;
SystemNavigationManager.GetForCurrentView().BackRequested += (s, a) =>
{
    if (Frame.CanGoBack)
    {
        Frame.GoBack();
        a.Handled = true;
    }
};

FileStream

uwpでのファイルアクセスの基本形。