Remove Material Frame Renderer from Frame element on dispose of renderer (#7752) fixes #7339

* [iOS] remove renderer from Frame on dispose

* - add uitests

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7339.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Text;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+using Xamarin.Forms.Core.UITests;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 7339, "[iOS] Material frame renderer not being cleared",
+		PlatformAffected.iOS)]
+#if UITEST
+	[NUnit.Framework.Category(UITestCategories.Shell)]
+#endif
+	public class Issue7339 : TestShell
+	{
+		protected override void Init()
+		{
+			Visual = VisualMarker.Material;
+			CreateContentPage("Item1").Content =
+				new StackLayout()
+				{
+					Children =
+					{
+						new Frame()
+						{
+							Content = new Label()
+							{
+								Text = "Navigate between flyout items a few times. If app doesn't crash then test has passed"
+							}
+						}
+					}
+				};
+
+			CreateContentPage("Item2").Content =
+				new StackLayout() { Children = { new Frame() } };
+		}
+
+#if UITEST
+		[Test]
+		public void MaterialFrameDisposesCorrectly()
+		{
+			TapInFlyout("Item1");
+			TapInFlyout("Item2");
+			TapInFlyout("Item1");
+			TapInFlyout("Item2");
+		}
+#endif
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -28,6 +28,7 @@
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue6889.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue6945.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7313.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7556.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7329.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7290.cs" />
@@ -58,6 +59,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue7338.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ScrollToGroup.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)NestedCollectionViews.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7339.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellFlyoutBehavior.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7128.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellGestures.cs" />

Xamarin.Forms.Material.iOS/MaterialFrameRenderer.cs

@@ -100,13 +100,17 @@ namespace Xamarin.Forms.Material.iOS
 				if (_packager == null)
 					return;
 
-				SetElement(null);
-
 				_packager.Dispose();
 				_packager = null;
 
 				_tracker.Dispose();
 				_tracker = null;
+
+				if (Element != null)
+				{
+					Element.ClearValue(Platform.iOS.Platform.RendererProperty);
+					SetElement(null);
+				}
 			}
 
 			base.Dispose(disposing);