public AppNavigationPage()
 {
     InitializeComponent();
     Page = this;
     if (BindingContext == null)
     {
         BindingContext = new AppNavigationBaseViewModel();
     }
 }
        protected override async void OnAppearing()
        {
            base.OnAppearing();
            Vm = ViewModel;

            await ViewModel.InitializeAsync();

            if (!ViewModel.SelectedNavigationPage.HasValue)
            {
                SetHomePage();
            }
            else
            {
                Page.SetPageContentPage();
            }
        }