IConfirmNavigationAsync.CanNavigateAsync not called from iOS "Back" Button

[munkii]

I have implemented IConfirmNavigationAsync.CanNavigateAsync on a ViewModel.

When the user presses the Back arrow in the Navbar in Android CanNavigateAsync is called and I can stop the Navigation if needed,

When the user presses the "Back" button in the Navigation Bar in iOS CanNavigateAsync is not called. I assume this should just work without me having to do anything particular.

The View\ViewModel is not being loaded modally and is simply using the INavigationService. What should I be doing?

var navigationParams = new NavigationParameters();

if (data != null)
{
    navigationParams.Add("initData", data);
}

if (animate == true)
{
    navigationParams.Add(KnownNavigationParameters.Animated, true);
}

if (modal == true)
{
    navigationParams.Add(KnownNavigationParameters.UseModalNavigation, true);
}

await this.NavigationService.NavigateAsync(typeof(T).Name, navigationParams);