[Mac] NavigationPageRenderer amendments RE: Issue4388 (#4607) #4388 #4389

* crash fixes https://github.com/xamarin/Xamarin.Forms/issues/4388

* Subview Z-index fix

* [MacOS] Dispose cleanup

* Added WantsLayer prop to Insert method

* Added disposing check to ViewRenderer

Xamarin.Forms.ControlGallery.MacOS/Xamarin.Forms.ControlGallery.MacOS.csproj

@@ -115,7 +115,7 @@
       <Name>Xamarin.Forms.Maps</Name>
     </ProjectReference>
     <ProjectReference Include="..\Xamarin.Forms.Platform\Xamarin.Forms.Platform.csproj">
-      <Project>{67F9D3A8-F71E-4428-913F-C37AE82CDB24}</Project>
+      <Project>{D31A6537-ED9C-4EBD-B231-A8D4FE44126A}</Project>
       <Name>Xamarin.Forms.Platform</Name>
     </ProjectReference>
     <ProjectReference Include="..\Xamarin.Forms.Platform.MacOS\Xamarin.Forms.Platform.MacOS.csproj">

Xamarin.Forms.Platform.MacOS/Cells/ViewCellNSView.cs

@@ -41,8 +41,7 @@ namespace Xamarin.Forms.Platform.MacOS
 				IVisualElementRenderer renderer;
 				if (_rendererRef != null && _rendererRef.TryGetTarget(out renderer) && renderer.Element != null)
 				{
-					Platform.DisposeModelAndChildrenRenderers(renderer.Element);
-
+					renderer.Element.DisposeModalAndChildRenderers();
 					_rendererRef = null;
 				}
 			}
@@ -99,7 +98,7 @@ namespace Xamarin.Forms.Platform.MacOS
 				{
 					//when cells are getting reused the element could be already set to another cell
 					//so we should dispose based on the renderer and not the renderer.Element
-					Platform.DisposeRendererAndChildren(renderer);
+					renderer.Element.DisposeModalAndChildRenderers();
 					renderer = GetNewRenderer();
 				}
 			}

Xamarin.Forms.Platform.MacOS/ModalPageTracker.cs

@@ -66,7 +66,7 @@ namespace Xamarin.Forms.Platform.MacOS
 				if (disposing)
 				{
 					foreach (var modal in _modals)
-						Platform.DisposeModelAndChildrenRenderers(modal);
+						modal.DisposeModalAndChildRenderers();
 					_renderer = null;
 				}
 				_disposed = true;
@@ -76,7 +76,7 @@ namespace Xamarin.Forms.Platform.MacOS
 		void HandleChildRemoved(object sender, ElementEventArgs e)
 		{
 			var view = e.Element;
-			Platform.DisposeModelAndChildrenRenderers(view);
+			view.DisposeModalAndChildRenderers();
 		}
 
 		Task PresentModalAsync(Page modal, bool animated)
@@ -124,7 +124,7 @@ namespace Xamarin.Forms.Platform.MacOS
 							: NSViewControllerTransitionOptions.None;
 
 			var task = _renderer.HandleAsyncAnimation(controller, toViewController, option,
-				() => Platform.DisposeModelAndChildrenRenderers(modal), modal);
+				() => modal.DisposeModalAndChildRenderers() , modal);
 			return task;
 		}
 	}

Xamarin.Forms.Platform.MacOS/NativeToolbarTracker.cs

@@ -193,6 +193,32 @@ namespace Xamarin.Forms.Platform.MacOS
 			}
 		}
 
+		internal void UpdateNavigationItems(bool forceShowBackButton = false)
+		{
+			if (_toolbar == null || _navigation == null || _navigationGroup == null)
+				return;
+			var items = new List<ToolbarItem>();
+			if (ShowBackButton(forceShowBackButton))
+			{
+				var backButtonItem = new ToolbarItem
+				{
+					Text = GetPreviousPageTitle(),
+					Command = new Command(async () => await NavigateBackFrombackButton())
+				};
+				items.Add(backButtonItem);
+			}
+
+			UpdateGroup(_navigationGroup, items, BackButtonItemWidth, -1);
+
+			var navItemBack = _navigationGroup.Items.FirstOrDefault();
+			if (navItemBack != null)
+			{
+				navItemBack.Button.Image = NSImage.ImageNamed(NSImageName.GoLeftTemplate);
+				navItemBack.Button.SizeToFit();
+				navItemBack.Button.AccessibilityTitle = "NSBackButton";
+			}
+		}
+
 		void UpdateBarBackgroundColor()
 		{
 			var bgColor = GetBackgroundColor().CGColor;
@@ -223,12 +249,12 @@ namespace Xamarin.Forms.Platform.MacOS
 				await popAsyncInner;
 		}
 
-		bool ShowBackButton()
+		bool ShowBackButton(bool forceShowBackButton)
 		{
 			if (_navigation == null)
 				return false;
 
-			return NavigationPage.GetHasBackButton(_navigation.CurrentPage) && !IsRootPage();
+			return NavigationPage.GetHasBackButton(_navigation.CurrentPage) && (forceShowBackButton || !IsRootPage());
 		}
 
 		bool IsRootPage()
@@ -320,32 +346,6 @@ namespace Xamarin.Forms.Platform.MacOS
 			UpdateGroup(_toolbarGroup, currentPage.ToolbarItems, ToolbarItemWidth, ToolbarItemSpacing);
 		}
 
-		void UpdateNavigationItems()
-		{
-			if (_toolbar == null || _navigation == null || _navigationGroup == null)
-				return;
-			var items = new List<ToolbarItem>();
-			if (ShowBackButton())
-			{
-				var backButtonItem = new ToolbarItem
-				{
-					Text = GetPreviousPageTitle(),
-					Command = new Command(async () => await NavigateBackFrombackButton())
-				};
-				items.Add(backButtonItem);
-			}
-
-			UpdateGroup(_navigationGroup, items, BackButtonItemWidth, -1);
-
-			var navItemBack = _navigationGroup.Items.FirstOrDefault();
-			if (navItemBack != null)
-			{
-				navItemBack.Button.Image = NSImage.ImageNamed(NSImageName.GoLeftTemplate);
-				navItemBack.Button.SizeToFit();
-				navItemBack.Button.AccessibilityTitle = "NSBackButton";
-			}
-		}
-
 		void UpdateTabbedItems()
 		{
 			if (_toolbar == null || _navigation == null || _tabbedGroup == null)

Xamarin.Forms.Platform.MacOS/Platform.cs

@@ -17,7 +17,7 @@ namespace Xamarin.Forms.Platform.MacOS
 					view.IsPlatformEnabled = newvalue != null;
 			});
 
-		readonly PlatformRenderer PlatformRenderer;
+		readonly PlatformRenderer _renderer;
 
 		bool _appeared;
 		bool _disposed;
@@ -26,12 +26,12 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		internal Platform()
 		{
-			PlatformRenderer = new PlatformRenderer(this);
+			_renderer = new PlatformRenderer(this);
 
 			MessagingCenter.Subscribe(this, Page.AlertSignalName, (Page sender, AlertArguments arguments) =>
 			{
 				var alert = NSAlert.WithMessage(arguments.Title, arguments.Cancel, arguments.Accept, null, arguments.Message);
-				var result = alert.RunSheetModal(PlatformRenderer.View.Window);
+				var result = alert.RunSheetModal(_renderer.View.Window);
 				if (arguments.Accept == null)
 					arguments.SetResult(result == 1);
 				else
@@ -57,7 +57,7 @@ namespace Xamarin.Forms.Platform.MacOS
 					alert.Layout();
 				}
 
-				var result = (int)alert.RunSheetModal(PlatformRenderer.View.Window);
+				var result = (int)alert.RunSheetModal(_renderer.View.Window);
 				var titleResult = string.Empty;
 				if (result == 1)
 					titleResult = arguments.Cancel;
@@ -102,8 +102,10 @@ namespace Xamarin.Forms.Platform.MacOS
 			MessagingCenter.Unsubscribe<Page, AlertArguments>(this, Page.AlertSignalName);
 			MessagingCenter.Unsubscribe<Page, bool>(this, Page.BusySetSignalName);
 
-			DisposeModelAndChildrenRenderers(Page);
-			PlatformRenderer.Dispose();
+			Page.DisposeModalAndChildRenderers();
+			//foreach (var modal in _modals)
+				//modal.DisposeModalAndChildRenderers();
+			_renderer.Dispose();
 		}
 
 		public static IVisualElementRenderer CreateRenderer(VisualElement element)
@@ -130,50 +132,7 @@ namespace Xamarin.Forms.Platform.MacOS
 			base.OnBindingContextChanged();
 		}
 
-		internal NSViewController ViewController => PlatformRenderer;
-
-		internal static void DisposeModelAndChildrenRenderers(Element view)
-		{
-			foreach (VisualElement child in view.Descendants())
-				DisposeRenderer(child);
-
-			DisposeRenderer(view);
-		}
-
-		static void DisposeRenderer(Element view)
-		{
-			IVisualElementRenderer renderer = GetRenderer((VisualElement)view);
-			if (renderer?.ViewController?.ParentViewController != null)
-				renderer?.ViewController?.RemoveFromParentViewController();
-
-			renderer?.NativeView?.RemoveFromSuperview();
-			renderer?.Dispose();
-
-			view.ClearValue(RendererProperty);
-		}
-
-		internal static void DisposeRendererAndChildren(IVisualElementRenderer rendererToRemove)
-		{
-			if (rendererToRemove == null || rendererToRemove.Element == null)
-				return;
-
-			if (GetRenderer(rendererToRemove.Element) == rendererToRemove)
-				rendererToRemove.Element.ClearValue(RendererProperty);
-
-			if (rendererToRemove.NativeView != null)
-			{
-				var subviews = rendererToRemove.NativeView.Subviews;
-				for (var i = 0; i < subviews.Length; i++)
-				{
-					var childRenderer = subviews[i] as IVisualElementRenderer;
-					if (childRenderer != null)
-						DisposeRendererAndChildren(childRenderer);
-				}
-
-				rendererToRemove.NativeView.RemoveFromSuperview();
-			}
-			rendererToRemove.Dispose();
-		}
+		internal NSViewController ViewController => _renderer;
 
 		internal void LayoutSubviews()
 		{
@@ -185,7 +144,7 @@ namespace Xamarin.Forms.Platform.MacOS
 			if (rootRenderer == null)
 				return;
 
-			rootRenderer.SetElementSize(new Size(PlatformRenderer.View.Bounds.Width, PlatformRenderer.View.Bounds.Height));
+			rootRenderer.SetElementSize(new Size(_renderer.View.Bounds.Width, _renderer.View.Bounds.Height));
 		}
 
 		internal void SetPage(Page newRoot)
@@ -203,14 +162,14 @@ namespace Xamarin.Forms.Platform.MacOS
 
 			Page.DescendantRemoved += HandleChildRemoved;
 
-			TargetApplication.NavigationProxy.Inner = PlatformRenderer.Navigation;
+			TargetApplication.NavigationProxy.Inner = _renderer.Navigation;
 		}
 
 		internal void DidAppear()
 		{
-			PlatformRenderer.Navigation.AnimateModalPages = false;
-			TargetApplication.NavigationProxy.Inner = PlatformRenderer.Navigation;
-			PlatformRenderer.Navigation.AnimateModalPages = true;
+			_renderer.Navigation.AnimateModalPages = false;
+			TargetApplication.NavigationProxy.Inner = _renderer.Navigation;
+			_renderer.Navigation.AnimateModalPages = true;
 		}
 
 		internal void WillAppear()
@@ -259,10 +218,10 @@ namespace Xamarin.Forms.Platform.MacOS
 				var viewRenderer = CreateRenderer(view);
 				SetRenderer(view, viewRenderer);
 
-				PlatformRenderer.View.AddSubview(viewRenderer.NativeView);
+				_renderer.View.AddSubview(viewRenderer.NativeView);
 				if (viewRenderer.ViewController != null)
-					PlatformRenderer.AddChildViewController(viewRenderer.ViewController);
-				viewRenderer.SetElementSize(new Size(PlatformRenderer.View.Bounds.Width, PlatformRenderer.View.Bounds.Height));
+					_renderer.AddChildViewController(viewRenderer.ViewController);
+				viewRenderer.SetElementSize(new Size(_renderer.View.Bounds.Width, _renderer.View.Bounds.Height));
 			}
 			else
 				Console.Error.WriteLine("A Renderer was already found, potential view double add");
@@ -271,7 +230,7 @@ namespace Xamarin.Forms.Platform.MacOS
 		void HandleChildRemoved(object sender, ElementEventArgs e)
 		{
 			var view = e.Element;
-			DisposeModelAndChildrenRenderers(view);
+			view.DisposeModalAndChildRenderers();
 		}
 	}
 }

Xamarin.Forms.Platform.MacOS/PlatformRenderer.cs

@@ -38,13 +38,17 @@ namespace Xamarin.Forms.Platform.MacOS
 		}
 
 		protected override void Dispose(bool disposing)
+		{
+			if (disposing)
 			{
 				if (!_disposed)
 				{
 					_platformNavigation.Dispose();
 					_platformNavigation = null;
+					Platform = null;
 				}
 				_disposed = true;
+			}
 			base.Dispose(disposing);
 		}
 	}

Xamarin.Forms.Platform.MacOS/Renderers/ListViewDataSource.cs

@@ -15,8 +15,9 @@ namespace Xamarin.Forms.Platform.MacOS
 		static int s_sectionCount;
 		readonly nfloat _defaultSectionHeight;
 		readonly Dictionary<DataTemplate, int> _templateToId = new Dictionary<DataTemplate, int>();
-		readonly NSTableView _nsTableView;
-		protected readonly ListView List;
+		NSTableView _nsTableView;
+		ListView List;
+		bool _disposed;
 
 		ITemplatedItemsView<Cell> TemplatedItemsView => List;
 
@@ -185,6 +186,26 @@ namespace Xamarin.Forms.Platform.MacOS
 			return nativeCell;
 		}
 
+		protected override void Dispose(bool disposing)
+		{
+			if (_disposed)
+				return;
+
+			if (disposing)
+			{
+				if (List != null)
+				{
+					List.ItemSelected -= OnItemSelected;
+					List = null;
+				}
+				_nsTableView = null;
+			}
+
+			_disposed = true;
+
+			base.Dispose(disposing);
+		}
+
 		protected virtual Cell GetCellForPath(NSIndexPath indexPath, bool isGroupHeader)
 		{
 			var templatedItems = TemplatedItemsView.TemplatedItems;

Xamarin.Forms.Platform.MacOS/Renderers/ListViewRenderer.cs

@@ -40,23 +40,13 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		protected override void Dispose(bool disposing)
 		{
-			if (disposing && !_disposed)
-			{
-				_disposed = true;
+			if (_disposed)
+				return;
 
-				var viewsToLookAt = new Stack<NSView>(Subviews);
-				while (viewsToLookAt.Count > 0)
+			if (disposing)
 			{
-					var view = viewsToLookAt.Pop();
-					var viewCellRenderer = view as ViewCellNSView;
-					if (viewCellRenderer != null)
-						viewCellRenderer.Dispose();
-					else
-					{
-						foreach (var child in view.Subviews)
-							viewsToLookAt.Push(child);
-					}
-				}
+				foreach (NSView subview in Subviews)
+					DisposeSubviews(subview);
 
 				if (Element != null)
 				{
@@ -64,21 +54,53 @@ namespace Xamarin.Forms.Platform.MacOS
 					templatedItems.CollectionChanged -= OnCollectionChanged;
 					templatedItems.GroupedCollectionChanged -= OnGroupedCollectionChanged;
 				}
+
+				if (_dataSource != null)
+				{
+					_dataSource.Dispose();
+					_dataSource = null;
 				}
 
-			if (disposing)
+				if (_headerRenderer != null)
 				{
-				ClearHeader();
+					_headerRenderer.Element?.DisposeModalAndChildRenderers();
+					_headerRenderer = null;
+				}
 				if (_footerRenderer != null)
 				{
-					Platform.DisposeModelAndChildrenRenderers(_footerRenderer.Element);
+					_footerRenderer.Element?.DisposeModalAndChildRenderers();
 					_footerRenderer = null;
 				}
 			}
 
+			_disposed = true;
+
+
 			base.Dispose(disposing);
 		}
 
+		void DisposeSubviews(NSView view)
+		{
+			var ver = view as IVisualElementRenderer;
+
+			if (ver == null)
+			{
+				// VisualElementRenderers should implement their own dispose methods that will appropriately dispose and remove their child views.
+				// Attempting to do this work twice could cause a SIGSEGV (only observed in iOS8), so don't do this work here.
+				// Non-renderer views, such as separator lines, etc., can be removed here.
+
+				if (view is NSClipView)
+					return;
+
+				foreach (NSView subView in view.Subviews)
+					DisposeSubviews(subView);
+
+				view.RemoveFromSuperview();
+			}
+
+			view.Dispose();
+		}
+
 		protected override void SetBackgroundColor(Color color)
 		{
 			base.SetBackgroundColor(color);
@@ -229,7 +251,7 @@ namespace Xamarin.Forms.Platform.MacOS
 			_table.HeaderView = null;
 			if (_headerRenderer == null)
 				return;
-			Platform.DisposeModelAndChildrenRenderers(_headerRenderer.Element);
+			_headerRenderer.Element.DisposeModalAndChildRenderers();
 			_headerRenderer = null;
 		}
 

Xamarin.Forms.Platform.MacOS/Renderers/NavigationPageRenderer.cs

@@ -88,9 +88,21 @@ namespace Xamarin.Forms.Platform.MacOS
 			{
 				if (Element != null)
 				{
-					NavigationPage?.SendDisappearing();
+					if (NavigationPage != null)
+					{
+						NavigationPage.PushRequested -= OnPushRequested;
+						NavigationPage.PopRequested -= OnPopRequested;
+						NavigationPage.PopToRootRequested -= OnPopToRootRequested;
+						NavigationPage.RemovePageRequested -= OnRemovedPageRequested;
+						NavigationPage.InsertPageBeforeRequested -= OnInsertPageBeforeRequested;
+						NavigationPage.Popped -= OnPopped;
+						NavigationPage.PoppedToRoot -= OnPoppedToRoot;
+
+						NavigationPage.SendDisappearing();
+					}
 					((Element as IPageContainer<Page>)?.CurrentPage as Page)?.SendDisappearing();
 					Element.PropertyChanged -= OnElementPropertyChanged;
+					Platform.SetRenderer(Element, null);
 					Element = null;
 				}
 
@@ -100,7 +112,19 @@ namespace Xamarin.Forms.Platform.MacOS
 				_events?.Dispose();
 				_events = null;
 
+				if(_currentStack != null)
+				{
+					foreach (var childPageWrapper in _currentStack)
+					{
+						childPageWrapper.Dispose();
+					}
+					_currentStack.Clear();
+					_currentStack = null;
+				}
+
+				Platform.NativeToolbarTracker.Navigation = null;
 				_disposed = true;
+
 			}
 			base.Dispose(disposing);
 		}
@@ -175,22 +199,19 @@ namespace Xamarin.Forms.Platform.MacOS
 		{
 			ConfigurePageRenderer();
 
-			var navPage = (NavigationPage)Element;
-
-			if (navPage.CurrentPage == null)
+			if (NavigationPage.CurrentPage == null)
 				throw new InvalidOperationException(
 					"NavigationPage must have a root Page before being used. Either call PushAsync with a valid Page, or pass a Page to the constructor before usage.");
 
-			Platform.NativeToolbarTracker.Navigation = navPage;
+			Platform.NativeToolbarTracker.Navigation = NavigationPage;
 
 			NavigationPage.PushRequested += OnPushRequested;
 			NavigationPage.PopRequested += OnPopRequested;
 			NavigationPage.PopToRootRequested += OnPopToRootRequested;
 			NavigationPage.RemovePageRequested += OnRemovedPageRequested;
 			NavigationPage.InsertPageBeforeRequested += OnInsertPageBeforeRequested;
-
-			navPage.Popped += (sender, e) => Platform.NativeToolbarTracker.UpdateToolBar();
-			navPage.PoppedToRoot += (sender, e) => Platform.NativeToolbarTracker.UpdateToolBar();
+			NavigationPage.Popped += OnPopped;
+			NavigationPage.PoppedToRoot += OnPoppedToRoot;
 
 			UpdateBarBackgroundColor();
 			UpdateBarTextColor();
@@ -199,7 +220,7 @@ namespace Xamarin.Forms.Platform.MacOS
 			_events.LoadEvents(NativeView);
 			_tracker = new VisualElementTracker(this);
 
-			navPage.Pages.ForEach(async p => await PushPageAsync(p, false));
+			NavigationPage.Pages.ForEach(async p => await PushPageAsync(p, false));
 
 			UpdateBackgroundColor();
 		}
@@ -213,6 +234,16 @@ namespace Xamarin.Forms.Platform.MacOS
 			return pageRenderer;
 		}
 
+		void OnPopped(object sender, NavigationEventArgs e)
+		{
+			Platform.NativeToolbarTracker.UpdateToolBar();
+		}
+
+		void OnPoppedToRoot(object sender, NavigationEventArgs e)
+		{
+			Platform.NativeToolbarTracker.UpdateToolBar();
+		}
+
 		void InsertPageBefore(Page page, Page before)
 		{
 			if (before == null)
@@ -229,17 +260,19 @@ namespace Xamarin.Forms.Platform.MacOS
 			var vc = CreateViewControllerForPage(page);
 			vc.SetElementSize(new Size(View.Bounds.Width, View.Bounds.Height));
 			page.Layout(new Rectangle(0, 0, View.Bounds.Width, View.Frame.Height));
+			vc.NativeView.WantsLayer = true;
 
-			var beforeViewController = Platform.GetRenderer(before).ViewController;
-			var beforeControllerIndex = ChildViewControllers.IndexOf(beforeViewController);
+			var beforeRenderer = Platform.GetRenderer(before);
+			var beforeControllerIndex = ChildViewControllers.IndexOf(beforeRenderer.ViewController);
 
 			InsertChildViewController(vc.ViewController, beforeControllerIndex);
-			View.AddSubview(vc.NativeView);
+			View.AddSubview(vc.NativeView, NSWindowOrderingMode.Below, beforeRenderer.NativeView);
 		}
 
 		void OnInsertPageBeforeRequested(object sender, NavigationRequestedEventArgs e)
 		{
 			InsertPageBefore(e.Page, e.BeforePage);
+			Platform.NativeToolbarTracker.UpdateNavigationItems(true);
 		}
 
 		void OnPopRequested(object sender, NavigationRequestedEventArgs e)
@@ -325,11 +358,11 @@ namespace Xamarin.Forms.Platform.MacOS
 
 			if (animated)
 			{
-				var previousPageRenderer = Platform.GetRenderer(previousPage);
+				var previousPageRenderer = CreateViewControllerForPage(previousPage);
 				var transitionStyle = NavigationPage.OnThisPlatform().GetNavigationTransitionPopStyle();
 
 				return await this.HandleAsyncAnimation(target.ViewController, previousPageRenderer.ViewController,
-					ToViewControllerTransitionOptions(transitionStyle), () => Platform.DisposeRendererAndChildren(target), true);
+					ToViewControllerTransitionOptions(transitionStyle), () => target.DisposeRendererAndChildren(), true);
 			}
 
 			RemovePage(page, false);

Xamarin.Forms.Platform.MacOS/Renderers/TableViewDataSource.cs

@@ -11,8 +11,9 @@ namespace Xamarin.Forms.Platform.MacOS
 		const string HeaderIdentifier = nameof(TextCell);
 		const string ItemIdentifier = nameof(ViewCell);
 
-		readonly NSTableView _nsTableView;
-		readonly TableView _tableView;
+		NSTableView _nsTableView;
+		TableView _tableView;
+		bool _disposed;
 
 		public TableViewDataSource(TableViewRenderer tableViewRenderer)
 		{
@@ -39,7 +40,7 @@ namespace Xamarin.Forms.Platform.MacOS
 			var cell = _tableView.Model.GetCell(sectionIndex, itemIndexInSection);
 			_tableView.Model.RowSelected(cell);
 			if (AutomaticallyDeselect)
-				_nsTableView.DeselectRow(row);
+				_nsTableView?.DeselectRow(row);
 		}
 
 		public override nint GetRowCount(NSTableView tableView)
@@ -91,6 +92,20 @@ namespace Xamarin.Forms.Platform.MacOS
 			return nativeCell;
 		}
 
+		protected override void Dispose(bool disposing)
+		{
+			if(disposing)
+			{
+				if(!_disposed)
+				{
+					_nsTableView = null;
+					_tableView = null;
+					_disposed = true;
+				}
+			}
+			base.Dispose(disposing);
+		}
+
 		void GetComputedIndexes(nint row, out int sectionIndex, out int itemIndexInSection, out bool isHeader)
 		{
 			var totalItems = 0;

Xamarin.Forms.Platform.MacOS/Renderers/TableViewRenderer.cs

@@ -7,6 +7,7 @@ namespace Xamarin.Forms.Platform.MacOS
 	public class TableViewRenderer : ViewRenderer<TableView, NSView>
 	{
 		const int DefaultRowHeight = 44;
+		bool _disposed;
 
 		internal NSTableView TableView { get; set; }
 
@@ -17,15 +18,19 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		protected override void Dispose(bool disposing)
 		{
+			if (_disposed)
+				return;
+
 			if (disposing)
 			{
 				var viewsToLookAt = new Stack<NSView>(Subviews);
 				while (viewsToLookAt.Count > 0)
 				{
 					var view = viewsToLookAt.Pop();
-					var viewCellRenderer = view as IVisualElementRenderer;
+					var viewCellRenderer = view as ViewCellNSView;
 					if (viewCellRenderer != null)
 					{
+						viewCellRenderer.RemoveFromSuperview();
 						viewCellRenderer.Dispose();
 					}
 					else
@@ -35,6 +40,7 @@ namespace Xamarin.Forms.Platform.MacOS
 					}
 				}
 			}
+			_disposed = true;
 
 			base.Dispose(disposing);
 		}

Xamarin.Forms.Platform.MacOS/Xamarin.Forms.Platform.macOS.csproj

@@ -237,10 +237,13 @@
       <Link>VisualElementRenderer.cs</Link>
     </Compile>
     <Compile Include="Extensions\NSMenuExtensions.cs" />
+    <Compile Include="..\Xamarin.Forms.Platform.iOS\DisposeHelpers.cs">
+      <Link>DisposeHelpers.cs</Link>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Xamarin.Forms.Platform\Xamarin.Forms.Platform.csproj">
-      <Project>{67F9D3A8-F71E-4428-913F-C37AE82CDB24}</Project>
+      <Project>{D31A6537-ED9C-4EBD-B231-A8D4FE44126A}</Project>
       <Name>Xamarin.Forms.Platform</Name>
     </ProjectReference>
     <ProjectReference Include="..\Xamarin.Forms.Core\Xamarin.Forms.Core.csproj">

Xamarin.Forms.Platform.iOS/DisposeHelpers.cs

@@ -1,4 +1,9 @@
+#if __MOBILE__
 namespace Xamarin.Forms.Platform.iOS
+#else
+
+namespace Xamarin.Forms.Platform.MacOS
+#endif
 {
 	internal static class DisposeHelpers
 	{
@@ -27,9 +32,11 @@ namespace Xamarin.Forms.Platform.iOS
 				{
 					if (renderer.ViewController != null)
 					{
+#if __MOBILE__
 						var modalWrapper = renderer.ViewController.ParentViewController as ModalWrapper;
 						if (modalWrapper != null)
 							modalWrapper.Dispose();
+#endif
 					}
 
 					renderer.NativeView.RemoveFromSuperview();
@@ -47,14 +54,16 @@ namespace Xamarin.Forms.Platform.iOS
 			if (rendererToRemove.Element != null && Platform.GetRenderer(rendererToRemove.Element) == rendererToRemove)
 				rendererToRemove.Element.ClearValue(Platform.RendererProperty);
 
+			if (rendererToRemove.NativeView != null)
+			{
 				var subviews = rendererToRemove.NativeView.Subviews;
 				for (var i = 0; i < subviews.Length; i++)
 				{
 					if (subviews[i] is IVisualElementRenderer childRenderer)
 						DisposeRendererAndChildren(childRenderer);
 				}
-
 				rendererToRemove.NativeView.RemoveFromSuperview();
+			}
 			rendererToRemove.Dispose();
 		}
 	}

Xamarin.Forms.Platform.iOS/ViewRenderer.cs

@@ -107,9 +107,13 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		protected override void Dispose(bool disposing)
 		{
-			base.Dispose(disposing);
+			if (disposing)
+			{
+				_elementPropertyChanged = null;
+				_controlChanging = null;
+				_controlChanged = null;
 
-			if (disposing && Control != null && ManageNativeControlLifetime)
+				if (Control != null && ManageNativeControlLifetime)
 				{
 					Control.RemoveFromSuperview();
 					Control.Dispose();
@@ -117,6 +121,9 @@ namespace Xamarin.Forms.Platform.MacOS
 				}
 			}
 
+			base.Dispose(disposing);
+		}
+
 		protected override void OnElementChanged(ElementChangedEventArgs<TView> e)
 		{
 			base.OnElementChanged(e);