From 295573f89dee8803bc60ca4a331c37473537eef3 Mon Sep 17 00:00:00 2001
From: Tim Johnson <tjohnson@aptos.com>
Date: Sun, 18 Oct 2020 22:59:57 -0400
Subject: [PATCH 1/4] Fixes #6761 - various memory leaks in listview with group
 headers.

---
 .../Issue6761.xaml                            |  79 ++++++++++
 .../Issue6761.xaml.cs                         | 141 ++++++++++++++++++
 ...rin.Forms.Controls.Issues.Shared.projitems |   6 +
 Xamarin.Forms.Core/TemplatedItemsList.cs      |  15 +-
 .../Cells/CellTableViewCell.cs                |   2 +-
 .../Cells/TextCellRenderer.cs                 |   2 +-
 .../Renderers/ListViewRenderer.cs             |  23 ++-
 7 files changed, 254 insertions(+), 14 deletions(-)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml
new file mode 100644
index 00000000000..59e9ea72231
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml
@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<controls:TestContentPage xmlns:controls="clr-namespace:Xamarin.Forms.Controls"
+             xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:d="http://xamarin.com/schemas/2014/forms/design"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"
+             x:Class="Xamarin.Forms.Controls.Issues.Issue6761">
+    <StackLayout>
+        <StackLayout Orientation="Horizontal">
+            <Button AutomationId="Issue6761Refresh" Clicked="RefreshItems" Text="Refresh" BackgroundColor="Cyan"/>
+            <Button AutomationId="Issue6761GC" Clicked="GCClick" Text="GC" BackgroundColor="Cyan"/>
+        </StackLayout>
+        <Label Text="Scroll the list, tap Refresh button a few times." />
+        <Label AutomationId="Issue6761Label" Text="{Binding DisposeString}"/>
+        <Label AutomationId="Issue6761Mem" Text="{Binding TotalMemory}"/>
+        <StackLayout Orientation="Horizontal">
+            <ListView
+                ItemsSource="{Binding ItemGroups}"
+                IsGroupingEnabled="True"
+                GroupDisplayBinding="{Binding GroupName}">
+                <ListView.ItemTemplate>
+                    <DataTemplate>
+                        <ViewCell>
+                            <StackLayout Margin="20">
+                                <Label Text="{Binding Name}" />
+                            </StackLayout>
+                        </ViewCell>
+                    </DataTemplate>
+                </ListView.ItemTemplate>
+            </ListView>
+            <ListView
+                ItemsSource="{Binding ItemGroups}"
+                IsGroupingEnabled="True">
+                <ListView.GroupHeaderTemplate>
+                    <DataTemplate>
+                        <ViewCell>
+                            <StackLayout Padding="15, 7, 15, 7" Orientation="Horizontal" BackgroundColor="#ffdab0">
+
+                                <Frame
+                                CornerRadius="14"
+                                BackgroundColor="#cf7806"
+                                Padding="2"
+                                Margin="0"
+                                HasShadow="false" >
+
+                                    <Frame
+                                    CornerRadius="12"
+                                    BackgroundColor="#ffdab0"
+                                    Padding="0"
+                                    Margin="0"
+                                    HasShadow="false" >
+
+                                        <Label
+                                        Text="{Binding GroupName}"
+                                        Margin="10, 5, 10, 5"
+                                        TextColor="#cf7806"
+                                        HorizontalTextAlignment="Center"
+                                        HorizontalOptions="Center"
+                                        VerticalTextAlignment="Center"
+                                        VerticalOptions="Center" />
+                                    </Frame>
+                                </Frame>
+                            </StackLayout>
+                        </ViewCell>
+                    </DataTemplate>
+                </ListView.GroupHeaderTemplate>
+                <ListView.ItemTemplate>
+                    <DataTemplate>
+                        <ViewCell>
+                            <StackLayout Margin="20">
+                                <Label Text="{Binding Name}" />
+                            </StackLayout>
+                        </ViewCell>
+                    </DataTemplate>
+                </ListView.ItemTemplate>
+            </ListView>
+        </StackLayout>
+    </StackLayout>
+</controls:TestContentPage>
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
new file mode 100644
index 00000000000..441d61b2329
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
@@ -0,0 +1,141 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System;
+using System.Collections.ObjectModel;
+using System.Runtime.CompilerServices;
+using System.ComponentModel;
+using System.Collections.Generic;
+
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 6761, "Memory leak in ListView with group headers on IOS", PlatformAffected.Default)]
+	public partial class Issue6761 : TestContentPage
+	{
+		public Issue6761()
+		{
+#if APP
+			InitializeComponent();
+#endif
+			BindingContext = viewModel = new ViewModelIssue6761();
+
+		}
+		protected override void Init()
+		{
+
+		}
+		int _count;
+		ViewModelIssue6761 viewModel;
+		IList<WeakReference<ModelIssue6761Group>> _weakList = new List<WeakReference<ModelIssue6761Group>>();
+		private void RefreshItems(object sender, EventArgs e)
+		{
+			foreach (var item in this.viewModel.ItemGroups)
+			{
+				item.Clear();
+			}
+			this.viewModel.ItemGroups.Clear();
+
+			for (int i = 0; i < 30; i++)
+			{
+				_count++;
+				var g1 = new ModelIssue6761Group("Group " + _count);
+				_weakList.Add(new WeakReference<ModelIssue6761Group>(g1));
+				this.viewModel.ItemGroups.Add(g1);
+			}
+
+			CleanAndReport();
+		}
+
+		private void GCClick(object sender, EventArgs e)
+		{
+			CleanAndReport();
+		}
+		void CleanAndReport()
+		{ 
+			GC.Collect();
+			GC.WaitForPendingFinalizers();
+			GC.Collect();
+
+			CleanWeakList(_weakList);
+			viewModel.DisposeString = $"{_weakList.Count} object(s) alive";
+
+			string report = $"MEMORY:{GC.GetTotalMemory(true)}";
+			viewModel.TotalMemory = report;
+		}
+
+		private void CleanWeakList(IList<WeakReference<ModelIssue6761Group>> weakList)
+		{
+			ModelIssue6761Group item;
+			for (int i = weakList.Count-1; i >= 0; i--)
+			{
+				if (!weakList[i].TryGetTarget(out item))
+				{
+					weakList.RemoveAt(i);
+				}
+			}
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class ViewModelIssue6761 : INotifyPropertyChanged
+	{
+		public ObservableCollection<ModelIssue6761Group> ItemGroups { get; set; } = new ObservableCollection<ModelIssue6761Group>();
+		public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
+
+		private void NotifyPropertyChanged([CallerMemberName] string propertyName = null)
+		{
+			this.PropertyChanged?.Invoke(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
+		}
+
+
+		string _DisposeString;
+		public string DisposeString
+		{
+			get { return _DisposeString; } 
+			set
+			{
+				_DisposeString = value;
+				NotifyPropertyChanged();
+			}
+		}
+
+		string _totalMemory;
+		public string TotalMemory 
+		{
+			get => _totalMemory;
+			set
+			{
+				_totalMemory = value;
+				NotifyPropertyChanged();
+			}
+		}
+
+		public ViewModelIssue6761()
+		{
+
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class ModelIssue6761Group : ObservableCollection<ModelIssue6761>
+	{
+		public ModelIssue6761Group(string name)
+		{
+			GroupName = name;
+		}
+		public string GroupName { get; set; }
+
+	}
+
+	[Preserve(AllMembers = true)]
+	public class ModelIssue6761
+	{
+		public ModelIssue6761(string name)
+		{
+			Name = name;
+		}
+		public string Name { get; set; }
+
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index 401138aee94..a1640b5798b 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -1606,6 +1606,9 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue11081.xaml.cs" >
       <DependentUpon>Issue11081.xaml</DependentUpon>
     </Compile>
+    <Compile Update="$(MSBuildThisFileDirectory)Issue6761.xaml.cs">
+      <DependentUpon>Issue6761.xaml</DependentUpon>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Bugzilla22229.xaml">
@@ -1731,6 +1734,9 @@
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue4040.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue6761.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue8787.xaml" />
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue9771.xaml">
       <SubType>Designer</SubType>
diff --git a/Xamarin.Forms.Core/TemplatedItemsList.cs b/Xamarin.Forms.Core/TemplatedItemsList.cs
index 27a8333024e..4ea1081e2e6 100644
--- a/Xamarin.Forms.Core/TemplatedItemsList.cs
+++ b/Xamarin.Forms.Core/TemplatedItemsList.cs
@@ -231,18 +231,17 @@ public void Dispose()
 				return;
 
 			_itemsView.PropertyChanged -= BindableOnPropertyChanged;
+			ListProxy.CollectionChanged -= OnProxyCollectionChanged;
 
 			TItem header = HeaderContent;
 			if (header != null)
-				UnhookItem(header);
-
-			for (var i = 0; i < _templatedObjects.Count; i++)
 			{
-				TItem item = _templatedObjects[i];
-				if (item != null)
-					UnhookItem(item);
+				UnhookItem(header);
+				HeaderContent = null;
 			}
 
+			UnhookAndClear();
+
 			_disposed = true;
 		}
 
@@ -710,7 +709,7 @@ void GroupedReset()
 				_groupedItems.Clear();
 			}
 
-			_templatedObjects.Clear();
+			UnhookAndClear();
 
 			var i = 0;
 			foreach (object item in ListProxy)
@@ -815,6 +814,7 @@ void OnCollectionChangedGrouped(NotifyCollectionChangedEventArgs e)
 						til.CollectionChanged -= OnInnerCollectionChanged;
 						oldItems.Add(til);
 						_groupedItems.RemoveAt(index);
+						UnhookItem(_templatedObjects[index]);
 						_templatedObjects.RemoveAt(index);
 						til.Dispose();
 					}
@@ -839,6 +839,7 @@ void OnCollectionChangedGrouped(NotifyCollectionChangedEventArgs e)
 						oldItems.Add(til);
 
 						_groupedItems.RemoveAt(index);
+						UnhookItem(_templatedObjects[index]);
 						_templatedObjects.RemoveAt(index);
 
 						newItems.Add(InsertGrouped(e.NewItems[i], index));
diff --git a/Xamarin.Forms.Platform.iOS/Cells/CellTableViewCell.cs b/Xamarin.Forms.Platform.iOS/Cells/CellTableViewCell.cs
index 89f67cfaefd..0196275a090 100644
--- a/Xamarin.Forms.Platform.iOS/Cells/CellTableViewCell.cs
+++ b/Xamarin.Forms.Platform.iOS/Cells/CellTableViewCell.cs
@@ -8,7 +8,7 @@ public class CellTableViewCell : UITableViewCell, INativeElementView
 	{
 		Cell _cell;
 
-		public Action<object, PropertyChangedEventArgs> PropertyChanged;
+		public event PropertyChangedEventHandler PropertyChanged;
 
 		bool _disposed;
 
diff --git a/Xamarin.Forms.Platform.iOS/Cells/TextCellRenderer.cs b/Xamarin.Forms.Platform.iOS/Cells/TextCellRenderer.cs
index 867309338c9..c93249c87d7 100644
--- a/Xamarin.Forms.Platform.iOS/Cells/TextCellRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Cells/TextCellRenderer.cs
@@ -26,7 +26,7 @@ public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell,
 			SetRealCell(item, tvc);
 
 			tvc.Cell = textCell;
-			tvc.PropertyChanged = HandleCellPropertyChanged;
+			tvc.PropertyChanged += HandleCellPropertyChanged;
 
 			tvc.TextLabel.Text = textCell.Text;
 			tvc.DetailTextLabel.Text = textCell.Detail;
diff --git a/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs
index 79c528a506c..41a849379fb 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs
@@ -1161,7 +1161,7 @@ public override UIView GetViewForHeader(UITableView tableView, nint section)
 				header.Cell = cell;
 
 				var renderer = (CellRenderer)Internals.Registrar.Registered.GetHandlerForObject<IRegisterable>(cell);
-				header.SetTableViewCell(renderer.GetCell(cell, null, tableView));
+				header.SetTableViewCell(renderer.GetCell(cell, header.GetTableViewCell(), tableView));
 
 				return header;
 			}
@@ -1173,8 +1173,13 @@ public override void HeaderViewDisplayingEnded(UITableView tableView, UIView hea
 
 				if (headerView is HeaderWrapperView wrapper)
 				{
-					wrapper.Cell?.SendDisappearing();
-					wrapper.Cell = null;
+					if (wrapper.Cell != null)
+					{
+						wrapper.Cell.SendDisappearing();
+						wrapper.SetTableViewCell(null);
+						wrapper.Cell.DisposeModalAndChildRenderers();
+						wrapper.Cell = null;
+					}
 				}
 			}
 
@@ -1514,10 +1519,18 @@ public HeaderWrapperView(string reuseIdentifier) : base((NSString)reuseIdentifie
 
 		public void SetTableViewCell(UITableViewCell value)
 		{
-			if (ReferenceEquals(_tableViewCell, value)) return;
+			if (ReferenceEquals(_tableViewCell, value)) 
+				return;
+			
 			_tableViewCell?.RemoveFromSuperview();
 			_tableViewCell = value;
-			AddSubview(value);
+			if (value != null)
+				AddSubview(value);
+		}
+
+		public UITableViewCell GetTableViewCell()
+		{
+			return _tableViewCell;
 		}
 
 		public override void LayoutSubviews()

From 9241bf0352c0b9bdada90ef0699ffc1701dad07c Mon Sep 17 00:00:00 2001
From: Tim Johnson <tjohnson@aptos.com>
Date: Mon, 19 Oct 2020 22:08:41 -0400
Subject: [PATCH 2/4] add blank line at end of file

---
 .../Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
index 441d61b2329..9138c06d727 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
@@ -138,4 +138,4 @@ public ModelIssue6761(string name)
 		public string Name { get; set; }
 
 	}
-}
\ No newline at end of file
+}

From 094d8c9d970cdbf7c66dac8bb2d6fbf817f76e9b Mon Sep 17 00:00:00 2001
From: Tim Johnson <tjohnson@aptos.com>
Date: Tue, 20 Oct 2020 12:31:11 -0400
Subject: [PATCH 3/4] Fix issues with the test class & projecitems file.

---
 .../Issue6761.xaml.cs                         |  19 ++--
 ...rin.Forms.Controls.Issues.Shared.projitems | 105 +++++++++---------
 2 files changed, 61 insertions(+), 63 deletions(-)

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
index 9138c06d727..f39ccc542bd 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6761.xaml.cs
@@ -18,30 +18,31 @@ public Issue6761()
 #if APP
 			InitializeComponent();
 #endif
-			BindingContext = viewModel = new ViewModelIssue6761();
+			BindingContext = _viewModel = new ViewModelIssue6761();
 
 		}
+		
 		protected override void Init()
-		{
+        {
+        }
 
-		}
 		int _count;
-		ViewModelIssue6761 viewModel;
+		ViewModelIssue6761 _viewModel;
 		IList<WeakReference<ModelIssue6761Group>> _weakList = new List<WeakReference<ModelIssue6761Group>>();
 		private void RefreshItems(object sender, EventArgs e)
 		{
-			foreach (var item in this.viewModel.ItemGroups)
+			foreach (var item in this._viewModel.ItemGroups)
 			{
 				item.Clear();
 			}
-			this.viewModel.ItemGroups.Clear();
+			this._viewModel.ItemGroups.Clear();
 
 			for (int i = 0; i < 30; i++)
 			{
 				_count++;
 				var g1 = new ModelIssue6761Group("Group " + _count);
 				_weakList.Add(new WeakReference<ModelIssue6761Group>(g1));
-				this.viewModel.ItemGroups.Add(g1);
+				this._viewModel.ItemGroups.Add(g1);
 			}
 
 			CleanAndReport();
@@ -58,10 +59,10 @@ void CleanAndReport()
 			GC.Collect();
 
 			CleanWeakList(_weakList);
-			viewModel.DisposeString = $"{_weakList.Count} object(s) alive";
+			_viewModel.DisposeString = $"{_weakList.Count} object(s) alive";
 
 			string report = $"MEMORY:{GC.GetTotalMemory(true)}";
-			viewModel.TotalMemory = report;
+			_viewModel.TotalMemory = report;
 		}
 
 		private void CleanWeakList(IList<WeakReference<ModelIssue6761Group>> weakList)
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index a1640b5798b..fb81dc8ecb8 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -35,6 +35,7 @@
       <DependentUpon>Issue11794.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11769.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue6761.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8613.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9137.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8691.cs" />
@@ -87,7 +88,7 @@
       <SubType>Code</SubType>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9006.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8207.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8207.xaml.cs">
       <DependentUpon>Issue8207.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue6362.cs" />
@@ -319,7 +320,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)CollectionViewBoundMultiSelection.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CollectionViewBoundSingleSelection.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue5765.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue4684.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue4684.xaml.cs">
       <DependentUpon>Issue4684.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue4992.xaml.cs">
@@ -1339,7 +1340,7 @@
       <DependentUpon>Issue7035.xaml</DependentUpon>
       <SubType>Code</SubType>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue7525.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7525.xaml.cs">
       <DependentUpon>Issue7525.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue7395.cs" />
@@ -1374,70 +1375,70 @@
       <SubType>Code</SubType>
       <DependentUpon>Issue6932_emptyviewstring.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8417.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8417.xaml.cs">
       <DependentUpon>Issue8417.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8647.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7510.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8557.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8557.xaml.cs">
       <DependentUpon>Issue8557.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8753.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8693.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue7813.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7813.xaml.cs">
       <DependentUpon>Issue7813.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8638.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8638.xaml.cs">
       <DependentUpon>Issue8638.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8294.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8392.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8672.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8779.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8779.xaml.cs">
       <DependentUpon>Issue8779.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8806.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8781.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8781.xaml.cs">
       <DependentUpon>Issue8781.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8782.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8782.xaml.cs">
       <DependentUpon>Issue8782.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8821.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8326.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8326.xaml.cs">
       <DependentUpon>Issue8326.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8449.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8449.xaml.cs">
       <DependentUpon>Issue8449.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue7875.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8973.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue7924.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7924.xaml.cs">
       <DependentUpon>Issue7924.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8461.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8777.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9143.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9588.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9588.xaml.cs">
       <DependentUpon>Issue9588.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9329.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9734.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9734.xaml.cs">
       <DependentUpon>Issue9734.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8767.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8767.xaml.cs">
       <DependentUpon>Issue8767.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8778.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8778.xaml.cs">
       <DependentUpon>Issue8778.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9646.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9646.xaml.cs">
       <DependentUpon>Issue9646.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9735.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9735.xaml.cs">
       <DependentUpon>Issue9735.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9305.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9305.xaml.cs">
       <DependentUpon>Issue9305.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9767.cs" />
@@ -1446,14 +1447,14 @@
       <DependentUpon>Issue7856_1.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9054.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9326.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9326.xaml.cs">
       <DependentUpon>Issue9326.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8689.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8689.xaml.cs">
       <DependentUpon>Issue9279.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9306.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue9417.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9417.xaml.cs">
       <DependentUpon>Issue9417.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8272.cs" />
@@ -1468,20 +1469,20 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue10438.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10530.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7780.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue8958.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue8958.xaml.cs">
       <DependentUpon>Issue8958.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue10679.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue10679.xaml.cs">
       <DependentUpon>Issue10679.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue10735.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue10735.xaml.cs">
       <DependentUpon>Issue10735.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue10497.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue10477.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue10477.xaml.cs">
       <DependentUpon>Issue10477.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue10875.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue10875.xaml.cs">
       <DependentUpon>Issue10875.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue10708.cs" />
@@ -1519,91 +1520,87 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue11031.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11018.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10940.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11190.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11190.xaml.cs">
       <DependentUpon>Issue11190.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11050.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11050.xaml.cs">
       <DependentUpon>Issue11050.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9456.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue10908.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue10908.xaml.cs">
       <DependentUpon>Issue10908.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11132.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11113.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11113.xaml.cs">
       <DependentUpon>Issue11113.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue10182.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11107.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11286.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)RectTest.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)RectTest.xaml.cs">
       <DependentUpon>RectTest.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11224.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11224.xaml.cs">
       <DependentUpon>Issue11224.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11262.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11262.xaml.cs">
       <DependentUpon>Issue11262.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11120.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11120.xaml.cs">
       <DependentUpon>Issue11120.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11291.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11244.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11272.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11333.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11333.xaml.cs">
       <DependentUpon>Issue11333.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11314.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11413.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11413.xaml.cs">
       <DependentUpon>Issue11413.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11563.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11547.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11547.xaml.cs">
       <DependentUpon>Issue11547.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue9451.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11374.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11374.xaml.cs">
       <DependentUpon>Issue11374.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11430.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11247.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10608.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11875.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11875.xaml.cs">
       <DependentUpon>Issue11875.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11737.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11737.xaml.cs">
       <DependentUpon>Issue11737.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11764.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11764.xaml.cs">
       <DependentUpon>Issue11764.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11573.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11573.xaml.cs">
       <DependentUpon>Issue11573.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11858.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9210.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11865.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11653.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11653.xaml.cs">
       <DependentUpon>Issue11653.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue11869.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11723.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11737.xaml.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11764.xaml.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11573.xaml.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11496.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue12134.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11963.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11831.xaml.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11496.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11496.xaml.cs">
       <DependentUpon>Issue11496.xaml</DependentUpon>
     </Compile>
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11209.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11209.xaml.cs">
       <DependentUpon>Issue11209.xaml</DependentUpon>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue10454.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Issue11081.xaml.cs" >
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11081.xaml.cs">
       <DependentUpon>Issue11081.xaml</DependentUpon>
     </Compile>
     <Compile Update="$(MSBuildThisFileDirectory)Issue6761.xaml.cs">
@@ -1895,7 +1892,7 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue11875.xaml">
-     <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue11653.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
@@ -2414,4 +2411,4 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
   </ItemGroup>
-</Project>
+</Project>
\ No newline at end of file

From 1ca198cd7005a4765283c078423a228ef28ad838 Mon Sep 17 00:00:00 2001
From: Tim Johnson <tjohnson@aptos.com>
Date: Thu, 4 Feb 2021 22:38:34 -0500
Subject: [PATCH 4/4] Fix failing unit tests
 (TemplatedItemsListTests.HookAndUnhookGroupOnReplace,
 TemplatedItemsListTests.UnhookGroupOnRemoval)  - Unhook the header in the
 Dispose function only if it has a binding context as this is already being
 done in the in the case of the list remove/replace actions

---
 Xamarin.Forms.Core/TemplatedItemsList.cs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Xamarin.Forms.Core/TemplatedItemsList.cs b/Xamarin.Forms.Core/TemplatedItemsList.cs
index 4ea1081e2e6..a32f5c3a4d0 100644
--- a/Xamarin.Forms.Core/TemplatedItemsList.cs
+++ b/Xamarin.Forms.Core/TemplatedItemsList.cs
@@ -234,12 +234,12 @@ public void Dispose()
 			ListProxy.CollectionChanged -= OnProxyCollectionChanged;
 
 			TItem header = HeaderContent;
-			if (header != null)
+			if (header != null && header.BindingContext != null)
 			{
 				UnhookItem(header);
-				HeaderContent = null;
 			}
-
+			
+			HeaderContent = null;
 			UnhookAndClear();
 
 			_disposed = true;