How to access existing AppBarButton and disable it - windows

Question

Is there a way to access an existing AppBarButton and disable it programmatically when I'm on a specific page other than the MainPage?
<CommandBar Grid.Row="0">
<CommandBar.Content>
<Button
Style="{StaticResource NavigationBackButtonNormalStyle}"
Name="BackButton"
VerticalAlignment="Top"
Click="Back_Click"/>
</CommandBar.Content>
<AppBarButton Icon="Mail" Name="ContactUs"/>
</CommandBar>
Update
Main Page
public sealed partial class MainPage : Page
{
public static AppBarButton MyAppBarButton;
public MainPage()
{
this.InitializeComponent();
Current = this;
Frame_Main.Navigate(typeof(Frame1));
MyAppBarButton = AppBarButtonSettings;
}
public static MainPage Current;
private void Back_Click(object sender, RoutedEventArgs e)
{
On_BackRequested();
}
private bool On_BackRequested()
{
if (Frame_Main.CanGoBack)
{
Frame_Main.GoBack();
return true;
}
return false;
}
private void BackInvoked(KeyboardAccelerator sender, KeyboardAcceleratorInvokedEventArgs args)
{
On_BackRequested();
args.Handled = true;
}
private void AppBarButtonContactUs_Click(object sender, RoutedEventArgs e)
{
Frame_Main.Navigate(typeof(ContactUs));
}
}
Contact Us page
public sealed partial class ContactUs: Page
{
public ContactUs()
{
this.InitializeComponent();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
MainPage.Current.BackButton.Visibility = Visibility.Visible;
MainPage.Current.BackButton.IsEnabled = true;
MainPage.MyAppBarButton.IsEnabled = false;
}
}

Answer 1

Sure, derive from your code, you could access AppBarButton with name in the code behind. for example:
private void Btn_Click(object sender, RoutedEventArgs e)
{
ContactUs.IsEnabled = false;
}
Update
You could make static AppBarButton to record ContactUs and access with the page class name.
public static AppBarButton MyAppBarButton;
public TestPage()
{
this.InitializeComponent();
MyAppBarButton = ContactUs;
}
Usage
TestPage.MyAppBarButton.IsEnabled = false;