How to use ViewModelCloser to close the View of th

Question

In the MvvmCross v3, CustomerManagement example, the method void RequestClose(IMvxViewModel viewModel) closes the top View. How do you close the View of a ViewModel instead?

Answer 1

I wouldn't use that ViewModelCloser method - although it could be extended if you want to.

MvvmCross v3 removed the previous CloseViewModel method - because it didn't really work across all platforms and across all presentation styles - across all of navigation controllers, splitviews, tabs, flyouts, popups, dialogs, etc.

To replace it, v3 introduces a new ViewModel call:

    protected bool ChangePresentation(MvxPresentationHint hint)

This is matched in the UIs with an IMvxViewPresenter method:

    void ChangePresentation(MvxPresentationHint hint);

To use this, you will need to:

1. Create a new Hint class - e.g. public class CustomPresentationHint : MvxPresentationHint { /* ... */ }

2. In each UI project, provide a custom presenter (normally by overriding CreateViewPresenter() in your Setup.cs class) - and in that custom presenter handle the ChangePresentationHint call:

         public void ChangePresentation(MvxPresentationHint hint)
         {
             if (hint is CustomPresentationHint)
             {
                  // your custom actions here
                  // - which may involve interacting with the RootFrame, with a NavigationController, with the AndroidFragment manager, etc
             }
         }
   

3. In your viewmodel, you can send a CustomPresentationHint when you want to.

I realise this is 'more work' than was required in vNext, but hopefully it's a more flexible, powerful approach.