Merge pull request #4131 from XAML-Knight/ListDetailsView_RemoveHardcoded

Update string reliance on WinUI NavigationView

Author: XAML-Knight

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ListDetailsView/ListDetailsView.bind

@@ -74,19 +74,20 @@
             </controls:ListDetailsView.NoSelectionContentTemplate>
             <controls:ListDetailsView.ListCommandBar>
                 <CommandBar>
+                    <!-- Button functionality to be implemented by developer -->
                     <AppBarButton Icon="Back" Label="Back"/>
                     <AppBarButton Icon="Forward" Label="Forward"/>
-
-          <CommandBar.Content>
-            <TextBlock Margin="12,14">
-              <Run Text="{Binding Emails.Count}" />
-              <Run Text="Items" />
-            </TextBlock>
-          </CommandBar.Content>
-        </CommandBar>
+                  <CommandBar.Content>
+                    <TextBlock Margin="12,14">
+                      <Run Text="{Binding Emails.Count}" />
+                      <Run Text="Items" />
+                    </TextBlock>
+                  </CommandBar.Content>
+                </CommandBar>
       </controls:ListDetailsView.ListCommandBar>
       <controls:ListDetailsView.DetailsCommandBar>
         <CommandBar>
+          <!-- Button functionality to be implemented by developer -->
           <AppBarButton Icon="MailReply" Label="Reply" />
           <AppBarButton Icon="MailReplyAll" Label="Reply All" />
           <AppBarButton Icon="MailForward" Label="Forward" />

Microsoft.Toolkit.Uwp.UI.Controls.Layout/ListDetailsView/ListDetailsView.cs

@@ -10,6 +10,7 @@
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Input;
 using Windows.UI.Xaml.Navigation;
+using NavigationView = Microsoft.UI.Xaml.Controls;
 
 namespace Microsoft.Toolkit.Uwp.UI.Controls
 {
@@ -42,12 +43,11 @@ public partial class ListDetailsView : ItemsControl
         private AppViewBackButtonVisibility? _previousSystemBackButtonVisibility;
         private bool _previousNavigationViewBackEnabled;
 
-        // Int used because the underlying type is an enum, but we don't have access to the enum
-        private int _previousNavigationViewBackVisibilty;
+        private NavigationView.NavigationViewBackButtonVisible _previousNavigationViewBackVisibilty;
+        private NavigationView.NavigationView _navigationView;
         private ContentPresenter _detailsPresenter;
         private VisualStateGroup _selectionStateGroup;
         private Button _inlineBackButton;
-        private object _navigationView;
         private Frame _frame;
 
         /// <summary>
@@ -199,7 +199,7 @@ private void OnLoaded(object sender, RoutedEventArgs e)
                     _frame.Navigating -= OnFrameNavigating;
                 }
 
-                _navigationView = this.FindAscendants().FirstOrDefault(p => p.GetType().FullName == "Microsoft.UI.Xaml.Controls.NavigationView");
+                _navigationView = this.FindAscendant<NavigationView.NavigationView>();
                 _frame = this.FindAscendant<Frame>();
                 if (_frame != null)
                 {
@@ -328,8 +328,6 @@ private void UpdateView(bool animate)
         /// </summary>
         private void SetBackButtonVisibility(ListDetailsViewState? previousState = null)
         {
-            const int backButtonVisible = 1;
-
             if (DesignMode.DesignModeEnabled)
             {
                 return;
@@ -358,7 +356,7 @@ private void SetBackButtonVisibility(ListDetailsViewState? previousState = null)
                     }
                     else
                     {
-                        SetNavigationViewBackButtonState(backButtonVisible, true);
+                        SetNavigationViewBackButtonState(NavigationView.NavigationViewBackButtonVisible.Visible, true);
                     }
                 }
                 else if (BackButtonBehavior != BackButtonBehavior.Manual)
@@ -441,27 +439,18 @@ private void SetVisualState(bool animate)
             VisualStateManager.GoToState(this, SelectedItem == null ? noSelectionState : hasSelectionState, animate);
         }
 
-        private void SetNavigationViewBackButtonState(int visible, bool enabled)
+        private void SetNavigationViewBackButtonState(NavigationView.NavigationViewBackButtonVisible visibility, bool enabled)
         {
             if (_navigationView == null)
             {
                 return;
             }
 
-            var navType = _navigationView.GetType();
-            var visibleProperty = navType.GetProperty("IsBackButtonVisible");
-            if (visibleProperty != null)
-            {
-                _previousNavigationViewBackVisibilty = (int)visibleProperty.GetValue(_navigationView);
-                visibleProperty.SetValue(_navigationView, visible);
-            }
+            _previousNavigationViewBackVisibilty = _navigationView.IsBackButtonVisible;
+            _navigationView.IsBackButtonVisible = visibility;
 
-            var enabledProperty = navType.GetProperty("IsBackEnabled");
-            if (enabledProperty != null)
-            {
-                _previousNavigationViewBackEnabled = (bool)enabledProperty.GetValue(_navigationView);
-                enabledProperty.SetValue(_navigationView, enabled);
-            }
+            _previousNavigationViewBackEnabled = _navigationView.IsBackEnabled;
+            _navigationView.IsBackEnabled = enabled;
         }
 
         private void SetDetailsContent()