Prism Sample 22-ConfirmCancelNavigation

导航到一个视图，如果在离开这个视图时需要确认，在VM中实现以下接口

public class ViewAViewModel : BindableBase, IConfirmNavigationRequest
    {
        public ViewAViewModel()
        {

        }

        public void ConfirmNavigationRequest(NavigationContext navigationContext, Action<bool> continuationCallback)
        {
            bool result = true;

            if (MessageBox.Show("Do you to navigate?", "Navigate?", MessageBoxButton.YesNo) == MessageBoxResult.No)
                result = false;

            continuationCallback(result);
        }

        public bool IsNavigationTarget(NavigationContext navigationContext)
        {
            return true;
        }

        public void OnNavigatedFrom(NavigationContext navigationContext)
        {

        }

        public void OnNavigatedTo(NavigationContext navigationContext)
        {

        }
    }