protected async override void OnNavigatingFrom()

in ContosoApp/Views/CustomerDetailPage.xaml.cs [87:126]
35 lines of code
6 McCabe index (conditional complexity)

        protected async override void OnNavigatingFrom(NavigatingCancelEventArgs e)
        {
            if (ViewModel.IsModified)
            {
                // Cancel the navigation immediately, otherwise it will continue at the await call. 
                e.Cancel = true;

                void resumeNavigation()
                {
                    if (e.NavigationMode == NavigationMode.Back)
                    {
                        Frame.GoBack();
                    }
                    else
                    {
                        Frame.Navigate(e.SourcePageType, e.Parameter, e.NavigationTransitionInfo);
                    }
                }

                var saveDialog = new SaveChangesDialog() { Title = $"Save changes?" };
                await saveDialog.ShowAsync();
                SaveChangesDialogResult result = saveDialog.Result;

                switch (result)
                {
                    case SaveChangesDialogResult.Save:
                        await ViewModel.SaveAsync();
                        resumeNavigation();
                        break;
                    case SaveChangesDialogResult.DontSave:
                        await ViewModel.RevertChangesAsync();
                        resumeNavigation();
                        break;
                    case SaveChangesDialogResult.Cancel:
                        break;
                }
            }

            base.OnNavigatingFrom(e);
        }