Close app after closing last fragment - xamarin.android

Question

I am writing an app with Xamarin.Android and MvvmCross. I am using fragments and have a "content container" design where I show the fragments in my content_frame view:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:local="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center">
<FrameLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true" />
</FrameLayout>
Everything works, and I can navigate through my app by showing/closing the fragments in my content_frame, but when I close the last fragment, instead of closing the app, it shows a blank screen instead. I reckon I can fix this in my MvxAppCompatViewPresenter class but I don't know how? I currently don't have anything in my view presenter:
public class ViewPresenter : MvxAppCompatViewPresenter
{
public ViewPresenter(IEnumerable<Assembly> androidViewAssemblies) : base(androidViewAssemblies)
{
}
public override void Show(MvxViewModelRequest request)
{
base.Show(request);
}
public override void Close(IMvxViewModel viewModel)
{
base.Close(viewModel);
}
}
Here is the first fragment:
[MvxFragmentPresentation(typeof(LoginViewModel), Resource.Id.content_frame, true)]
[Register("myapp.droid.fragments.LoginSelectionFragment")]
public class LoginSelectionFragment : BaseFragment<LoginSelectionViewModel>
{
protected override int FragmentId => Resource.Layout.fragment_login_selection;
}

Answer 1

One of the approaches you can use, is to not add the fragments that are starting fragments to the backstack by setting the MvxFragmentPresentation property AddToBackStack to false (false is also the default if no parameter is passed).
The idea there is that for the first fragment you would rely on the activity being added to the backstack. Essentially, the first fragment and the activity could then be considered the same with respect to the backstack, eliminating the blank screen.
However, this would only work if the starting fragments do not need to be added to the backstack, with in the same activity context, later in the navigational flow. In future versions of MvvmCross you would easily be able to overcome this limitation via the updated IMvxOverridePresentationAttribute.