Fixed Issue10679, avoid NRE accessing a disposed SwipeView (#10682)

Co-authored-by: Rui Marinho <me@ruimarinho.net>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue10679.xaml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<local:TestShell 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"
+             xmlns:local="using:Xamarin.Forms.Controls"
+             xmlns:issues="using:Xamarin.Forms.Controls.Issues"
+             x:Class="Xamarin.Forms.Controls.Issues.Issue10679">
+    <Shell.Resources>
+        <ResourceDictionary>
+
+            <Color x:Key="NavigationPrimary">#2196F3</Color>
+
+            <Style x:Key="BaseStyle"
+                   TargetType="Element">
+                <Setter Property="Shell.BackgroundColor" Value="{StaticResource NavigationPrimary}" />
+                <Setter Property="Shell.ForegroundColor" Value="White" />
+                <Setter Property="Shell.TitleColor" Value="White" />
+                <Setter Property="Shell.DisabledColor" Value="#B4FFFFFF" />
+                <Setter Property="Shell.UnselectedColor" Value="#95FFFFFF" />
+                <Setter Property="Shell.TabBarBackgroundColor" Value="{StaticResource NavigationPrimary}" />
+                <Setter Property="Shell.TabBarForegroundColor" Value="White" />
+                <Setter Property="Shell.TabBarUnselectedColor" Value="#95FFFFFF" />
+                <Setter Property="Shell.TabBarTitleColor" Value="White" />
+            </Style>
+
+            <Style BasedOn="{StaticResource BaseStyle}"
+                   TargetType="TabBar" />
+
+        </ResourceDictionary>
+    </Shell.Resources>
+    <ShellContent ContentTemplate="{DataTemplate issues:FirstIssue10679Page}" />
+</local:TestShell>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue10679.xaml.cs

@@ -0,0 +1,148 @@
+using System.Collections.Generic;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.Forms.Core.UITests;
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 10679, "SwipeView crash with NullReferenceException",
+		PlatformAffected.Android)]
+	public partial class Issue10679 : TestShell
+	{
+		public Issue10679()
+		{
+#if APP
+			Device.SetFlags(new List<string>(Device.Flags ?? new List<string>()) { "SwipeView_Experimental" });
+			InitializeComponent();
+#endif
+		}
+
+		protected override void Init()
+		{
+
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class FirstIssue10679Page : ContentPage
+	{
+		public FirstIssue10679Page()
+		{
+			Title = "Issue 10679";
+
+			var layout = new Grid();
+
+			var button = new Button
+			{
+				VerticalOptions = LayoutOptions.Center,
+				Text = "Go to Next Page"
+			};
+
+			layout.Children.Add(button);
+
+			Content = layout;
+
+			button.Clicked += async (sender, args) =>
+			{
+				await Shell.Current.Navigation.PushAsync(new SecondIssue10679Page()).ConfigureAwait(false);
+			};
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class SecondIssue10679Page : ContentPage
+	{
+		public SecondIssue10679Page()
+		{
+			var layout = new Grid();
+
+			var swipeView = new SwipeView();
+
+			var leftItem = new SwipeItem
+			{
+				BackgroundColor = Color.Red
+			};
+
+			var leftItems = new SwipeItems
+			{
+				Mode = SwipeMode.Execute,
+				SwipeBehaviorOnInvoked = SwipeBehaviorOnInvoked.Close
+			};
+
+			leftItems.Add(leftItem);
+
+			var rightItem = new SwipeItem
+			{
+				BackgroundColor = Color.Green
+			};
+
+			var rightItems = new SwipeItems
+			{
+				Mode = SwipeMode.Execute,
+				SwipeBehaviorOnInvoked = SwipeBehaviorOnInvoked.Close
+			};
+
+			rightItems.Add(rightItem);
+
+			var content = new Grid
+			{
+				BackgroundColor = Color.White
+			};
+
+			var contentLabel = new Label
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				Text = "Swipe Left or Right"
+			};
+
+			content.Children.Add(contentLabel);
+
+			swipeView.Content = content;
+			swipeView.LeftItems = leftItems;
+			swipeView.RightItems = rightItems;
+
+			layout.Children.Add(swipeView);
+
+			Content = layout;
+
+			leftItem.Invoked += async (sender, args) =>
+			{
+				Shell.Current.Navigation.InsertPageBefore(new ThirdIssue10679Page(), this);
+				_ = await Shell.Current.Navigation.PopAsync(false);
+			};
+
+			rightItem.Invoked += async (sender, args) =>
+			{
+				Shell.Current.Navigation.InsertPageBefore(new ThirdIssue10679Page(), this);
+				_ = await Shell.Current.Navigation.PopAsync(false);
+			};
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class ThirdIssue10679Page : ContentPage
+	{
+		public ThirdIssue10679Page()
+		{
+			var layout = new StackLayout();
+
+			var infoLabel = new Label
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				Text = "Without NullReferenceException, the test has passed."
+			};
+
+			layout.Children.Add(infoLabel);
+
+			Content = layout;
+		}
+	}
+}

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

@@ -1412,6 +1412,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue10530.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7780.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8958.xaml.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue10679.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10830.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10735.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10497.cs" />
@@ -1679,6 +1680,10 @@
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue8958.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue10679.xaml">        
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>    
+    </EmbeddedResource>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue10735.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>