From 247f758523c8bce9162b0a7192b24b53a9d4ae86 Mon Sep 17 00:00:00 2001
From: kicsiede <4233752+kicsiede@users.noreply.github.com>
Date: Wed, 8 May 2019 19:41:08 +0200
Subject: [PATCH] [iOS] Fix: memory leak when Navigation.RemovePage is used
 (#5695)

* Fix: memoryleak when Navigation.RemovePage is used

The leak occurs in a MasterDetailPage.Detail = NavigationPage(ContentPage) scenario if the ContentPage has ToolBarItems. (ToolBarItems create a strong dependency therefore the ViewController of the NavigationPage must be explicitly disposed)

* + unit test

* fix issue attribute
---
 .../Issue5695.cs                                   | 96 ++++++++++++++++++++++
 .../Xamarin.Forms.Controls.Issues.Shared.projitems |  1 +
 .../Renderers/NavigationRenderer.cs                |  1 +
 3 files changed, 98 insertions(+)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5695.cs

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5695.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5695.cs
new file mode 100644
index 0000000..ae13a19
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5695.cs
@@ -0,0 +1,96 @@
+using System;
+using System.Collections.Generic;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using NUnit.Framework;
+using Xamarin.UITest;
+using Xamarin.Forms.Core.UITests;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 5695, "Memory leak when Navigation.RemovePage", PlatformAffected.iOS)]
+	public class Issue5695 : TestMasterDetailPage
+    {
+		[Preserve(AllMembers = true)]
+		class LeakPage : ContentPage
+		{
+			public LeakPage()
+			{
+                ToolbarItems.Add(new ToolbarItem { Text = "Dummy" });
+			}
+		}
+
+		protected override void Init ()
+		{
+			var wref = new WeakReference(null);
+
+			var result = new Label { 
+				FontSize = 16,			
+				Text = "Click 'Push page'"
+			};
+
+			var checkResult = new Button
+			{
+				Text = "Check Result",
+				IsEnabled = false,
+				Command = new Command(() =>
+				{
+					GC.Collect();
+					GC.WaitForPendingFinalizers();
+					GC.Collect();
+
+					result.Text = wref.IsAlive ? "Failed" : "Success";
+				})
+			};
+
+			Detail = new NavigationPage(new LeakPage());
+
+            Master = new ContentPage
+            {
+                Title = "menu",
+			    Content = new StackLayout
+                {
+                    Children = {
+                        result,
+                        new Button
+                        {
+                            Text = "Push page",
+                            Command = new Command(async() => {
+
+                                await Detail.Navigation.PushAsync(new LeakPage());
+
+								var pageToRemove = Detail.Navigation.NavigationStack[0];
+								
+								Detail.Navigation.RemovePage(pageToRemove);
+
+								wref.Target = pageToRemove;
+
+								checkResult.IsEnabled = true;
+								result.Text = "You can check result";
+							})
+                        },
+						checkResult
+                    }
+                }
+			};
+		}
+
+#if UITEST
+		[Test]
+		public void Issue5695Test()
+		{
+			RunningApp.Tap(q => q.Marked("Push page"));
+			RunningApp.WaitForElement(q => q.Marked("Push page"));
+
+			RunningApp.WaitForElement(q => q.Marked("You can check result"));
+			RunningApp.Tap(q => q.Marked("Check Result"));
+
+			RunningApp.WaitForElement(q => q.Marked("Success"));
+		}
+#endif
+	}
+}
\ 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 c134900..1ed6663 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
@@ -465,6 +465,7 @@
       <DependentUpon>Issue5003.xaml</DependentUpon>
       <SubType>Code</SubType>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Issue5695.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue5535.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue5949.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue5949_1.xaml.cs">
diff --git a/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
index 3436edc..c38f4fc 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
@@ -587,6 +587,7 @@ namespace Xamarin.Forms.Platform.iOS
 				_removeControllers = _removeControllers.Remove(target);
 				ViewControllers = _removeControllers;
 			}
+			target.Dispose();
 			var parentingViewController = ViewControllers.Last() as ParentingViewController;
 			parentingViewController?.UpdateLeftBarButtonItem(page);
 		}
-- 
2.7.4