App.PromptToConfirmExit.cs

public bool PromptToConfirmExit
{
    get
    {
        bool promptToConfirmExit = false;
        if (MainPage is ContentPage)
        {
            promptToConfirmExit = true;
        }
        else if (MainPage is Xamarin.Forms.MasterDetailPage masterDetailPage
            && masterDetailPage.Detail is NavigationPage detailNavigationPage)
        {
            promptToConfirmExit = detailNavigationPage.Navigation.NavigationStack.Count <= 1;
        }
        else if (MainPage is NavigationPage mainPage)
        {
            if (mainPage.CurrentPage is TabbedPage tabbedPage
                && tabbedPage.CurrentPage is NavigationPage navigationPage)
            {
                promptToConfirmExit = navigationPage.Navigation.NavigationStack.Count <= 1;
            }
            else
            {
                promptToConfirmExit = mainPage.Navigation.NavigationStack.Count <= 1;
            }
        }
        else if (MainPage is TabbedPage tabbedPage
            && tabbedPage.CurrentPage is NavigationPage navigationPage)
        {
            promptToConfirmExit = navigationPage.Navigation.NavigationStack.Count <= 1;
        }
        return promptToConfirmExit;
    }
}