When swapping out ShellItems clear services

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellFlyoutTemplatedContentRenderer.cs

@@ -127,6 +127,14 @@ protected virtual void LoadView(IShellContext shellContext)
 
 				void InitialLoad(GenericGlobalLayoutListener listener, AView view)
 				{
+					// This means the handler was disconnected before the flyout was loaded
+					if (_shellContext?.Shell is null)
+					{
+						listener.Invalidate();
+						sfl.LayoutChanging -= OnFlyoutViewLayoutChanging;
+						return;
+					}
+
 					OnFlyoutViewLayoutChanging();
 
 					if (_flyoutContentView == null || ggll == null)

src/Controls/src/Core/PublicAPI/net-android/PublicAPI.Unshipped.txt

@@ -347,6 +347,7 @@ static Microsoft.Maui.Controls.Binding.Create<TSource, TProperty>(System.Func<TS
 *REMOVED*~static Microsoft.Maui.Controls.WebView.ControlsWebViewMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IWebView, Microsoft.Maui.Handlers.WebViewHandler>
 *REMOVED*static Microsoft.Maui.Controls.FlyoutPage.ControlsFlyoutPageMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IFlyoutView!, Microsoft.Maui.Handlers.FlyoutViewHandler!>!
 *REMOVED*static Microsoft.Maui.Controls.Toolbar.ControlsToolbarMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.Controls.Toolbar!, Microsoft.Maui.Handlers.ToolbarHandler!>!
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Embedding.EmbeddingExtensions
 static Microsoft.Maui.Controls.Embedding.EmbeddingExtensions.CreateEmbeddedWindowContext(this Microsoft.Maui.Hosting.MauiApp! mauiApp, Android.App.Activity! platformWindow) -> Microsoft.Maui.IMauiContext!
 static Microsoft.Maui.Controls.Embedding.EmbeddingExtensions.ToPlatformEmbedded(this Microsoft.Maui.IElement! element, Microsoft.Maui.IMauiContext! context) -> Android.Views.View!

src/Controls/src/Core/PublicAPI/net-ios/PublicAPI.Unshipped.txt

@@ -240,6 +240,7 @@ override Microsoft.Maui.Controls.SearchBar.IsEnabledCore.get -> bool
 ~Microsoft.Maui.Controls.WebView.UserAgent.set -> void
 ~override Microsoft.Maui.Controls.Region.Equals(object obj) -> bool
 ~override Microsoft.Maui.Controls.Shapes.Matrix.Equals(object obj) -> bool
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void
 ~static Microsoft.Maui.Controls.Region.FromRectangles(System.Collections.Generic.IEnumerable<Microsoft.Maui.Graphics.Rect> rectangles) -> Microsoft.Maui.Controls.Region
 ~static readonly Microsoft.Maui.Controls.InputView.CursorPositionProperty -> Microsoft.Maui.Controls.BindableProperty
 ~static readonly Microsoft.Maui.Controls.InputView.FontAttributesProperty -> Microsoft.Maui.Controls.BindableProperty

src/Controls/src/Core/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt

@@ -370,6 +370,7 @@ static Microsoft.Maui.Controls.Binding.Create<TSource, TProperty>(System.Func<TS
 *REMOVED*~static Microsoft.Maui.Controls.WebView.ControlsWebViewMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IWebView, Microsoft.Maui.Handlers.WebViewHandler>
 *REMOVED*static Microsoft.Maui.Controls.FlyoutPage.ControlsFlyoutPageMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IFlyoutView!, Microsoft.Maui.Handlers.FlyoutViewHandler!>!
 *REMOVED*static Microsoft.Maui.Controls.Toolbar.ControlsToolbarMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.Controls.Toolbar!, Microsoft.Maui.Handlers.ToolbarHandler!>!
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Embedding.EmbeddingExtensions
 static Microsoft.Maui.Controls.Embedding.EmbeddingExtensions.CreateEmbeddedWindowContext(this Microsoft.Maui.Hosting.MauiApp! mauiApp, UIKit.UIWindow! platformWindow) -> Microsoft.Maui.IMauiContext!
 static Microsoft.Maui.Controls.Embedding.EmbeddingExtensions.ToPlatformEmbedded(this Microsoft.Maui.IElement! element, Microsoft.Maui.IMauiContext! context) -> UIKit.UIView!

src/Controls/src/Core/PublicAPI/net-tizen/PublicAPI.Unshipped.txt

@@ -318,3 +318,4 @@ Microsoft.Maui.Controls.WebViewProcessTerminatedEventArgs
 Microsoft.Maui.Controls.WebViewProcessTerminatedEventArgs.WebViewProcessTerminatedEventArgs() -> void
 Microsoft.Maui.Controls.PlatformWebViewProcessTerminatedEventArgs
 Microsoft.Maui.Controls.PlatformWebViewProcessTerminatedEventArgs.PlatformWebViewProcessTerminatedEventArgs() -> void
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void

src/Controls/src/Core/PublicAPI/net-windows/PublicAPI.Unshipped.txt

@@ -357,6 +357,7 @@ static Microsoft.Maui.Controls.Binding.Create<TSource, TProperty>(System.Func<TS
 *REMOVED*~static Microsoft.Maui.Controls.WebView.ControlsWebViewMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IWebView, Microsoft.Maui.Handlers.WebViewHandler>
 *REMOVED*static Microsoft.Maui.Controls.FlyoutPage.ControlsFlyoutPageMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IFlyoutView!, Microsoft.Maui.Handlers.FlyoutViewHandler!>!
 *REMOVED*static Microsoft.Maui.Controls.Toolbar.ControlsToolbarMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.Controls.Toolbar!, Microsoft.Maui.Handlers.ToolbarHandler!>!
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Embedding.EmbeddingExtensions
 static Microsoft.Maui.Controls.Embedding.EmbeddingExtensions.CreateEmbeddedWindowContext(this Microsoft.Maui.Hosting.MauiApp! mauiApp, Microsoft.UI.Xaml.Window! platformWindow) -> Microsoft.Maui.IMauiContext!
 static Microsoft.Maui.Controls.Embedding.EmbeddingExtensions.ToPlatformEmbedded(this Microsoft.Maui.IElement! element, Microsoft.Maui.IMauiContext! context) -> Microsoft.UI.Xaml.FrameworkElement!

src/Controls/src/Core/PublicAPI/net/PublicAPI.Unshipped.txt

@@ -315,3 +315,4 @@ static Microsoft.Maui.Controls.Binding.Create<TSource, TProperty>(System.Func<TS
 *REMOVED*~static Microsoft.Maui.Controls.WebView.ControlsWebViewMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IWebView, Microsoft.Maui.Handlers.WebViewHandler>
 *REMOVED*static Microsoft.Maui.Controls.FlyoutPage.ControlsFlyoutPageMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IFlyoutView!, Microsoft.Maui.Handlers.FlyoutViewHandler!>!
 *REMOVED*static Microsoft.Maui.Controls.Toolbar.ControlsToolbarMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.Controls.Toolbar!, Microsoft.Maui.Handlers.ToolbarHandler!>!
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void

src/Controls/src/Core/PublicAPI/netstandard/PublicAPI.Unshipped.txt

@@ -315,3 +315,4 @@ static Microsoft.Maui.Controls.Binding.Create<TSource, TProperty>(System.Func<TS
 *REMOVED*~static Microsoft.Maui.Controls.WebView.ControlsWebViewMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IWebView, Microsoft.Maui.Handlers.WebViewHandler>
 *REMOVED*static Microsoft.Maui.Controls.FlyoutPage.ControlsFlyoutPageMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.IFlyoutView!, Microsoft.Maui.Handlers.FlyoutViewHandler!>!
 *REMOVED*static Microsoft.Maui.Controls.Toolbar.ControlsToolbarMapper -> Microsoft.Maui.IPropertyMapper<Microsoft.Maui.Controls.Toolbar!, Microsoft.Maui.Handlers.ToolbarHandler!>!
+~override Microsoft.Maui.Controls.ShellContent.OnPropertyChanged(string propertyName = null) -> void

src/Controls/src/Core/Shell/Shell.cs

@@ -1634,8 +1634,18 @@ protected virtual void OnNavigating(ShellNavigatingEventArgs args)
 		static void OnCurrentItemChanged(BindableObject bindable, object oldValue, object newValue)
 		{
 			if (oldValue is ShellItem oldShellItem)
+			{
 				oldShellItem.SendDisappearing();
 
+				foreach(var section in oldShellItem.Items)
+				{
+					foreach(var content in section.Items)
+					{
+						content.EvaluateDisconnect();
+					}
+				}
+			}
+
 			if (newValue == null)
 				return;
 

src/Controls/src/Core/Shell/ShellContent.cs

@@ -54,6 +54,7 @@ public DataTemplate ContentTemplate
 		EventHandler _isPageVisibleChanged;
 		event EventHandler IShellContentController.IsPageVisibleChanged { add => _isPageVisibleChanged += value; remove => _isPageVisibleChanged -= value; }
 
+		bool _createdViaService;
 		Page IShellContentController.GetOrCreateContent()
 		{
 			var template = ContentTemplate;
@@ -74,11 +75,19 @@ Page IShellContentController.GetOrCreateContent()
 						var services = Parent?.FindMauiContext()?.Services;
 						if (services is not null)
 						{
-							return Extensions.DependencyInjection.ActivatorUtilities.GetServiceOrCreateInstance(services, template.Type);
+							var result = services.GetService(template.Type);
+							if (result is not null)
+							{
+								_createdViaService = true;
+								return result;
+							}
 						}
-						return Activator.CreateInstance(template.Type);
+
+						_createdViaService = false;
+						return Extensions.DependencyInjection.ActivatorUtilities.CreateInstance(services, template.Type);
 					};
 				}
+
 				result = ContentCache ?? (Page)template.CreateContent(content, this);
 				ContentCache = result;
 			}
@@ -108,7 +117,10 @@ void IShellContentController.RecyclePage(Page page)
 		Page _contentCache;
 
 		/// <include file="../../../docs/Microsoft.Maui.Controls/ShellContent.xml" path="//Member[@MemberName='.ctor']/Docs/*" />
-		public ShellContent() => ((INotifyCollectionChanged)MenuItems).CollectionChanged += MenuItemsCollectionChanged;
+		public ShellContent()
+		{
+			((INotifyCollectionChanged)MenuItems).CollectionChanged += MenuItemsCollectionChanged;
+		}
 
 		internal bool IsVisibleContent => Parent is ShellSection shellSection && shellSection.IsVisibleSection && shellSection.CurrentItem == this;
 
@@ -187,18 +199,77 @@ Page ContentCache
 				var oldCache = _contentCache;
 				_contentCache = value;
 				if (oldCache != null)
+				{
 					RemoveLogicalChild(oldCache);
+					oldCache.Unloaded -= OnPageUnloaded;
+				}
 
-				if (value != null && value.Parent != this)
+				if (value is not null && value.Parent != this)
 				{
 					AddLogicalChild(value);
+
+					if (_createdViaService)
+					{
+						value.Unloaded += OnPageUnloaded;
+					}
 				}
 
-				if (Parent != null)
+				if (Parent is not null)
+				{
 					((ShellSection)Parent).UpdateDisplayedPage();
+				}
 			}
 		}
 
+		internal void EvaluateDisconnect()
+		{
+			if(!_createdViaService)
+				return;
+
+			// If the user has set the IsVisible property on this shell content to false
+			bool disconnect = true;
+
+			if(Parent is ShellSection shellSection &&
+				shellSection.Parent is ShellItem shellItem &&
+				shellItem.Parent is Shell shell)
+			{
+				disconnect = 
+					!this.IsVisible || // user has set the IsVisible property to false
+					(_contentCache is not null && !_contentCache.IsVisible) || // user has set IsVisible on the Page to false
+					shell.CurrentItem != shellItem || // user has navigated to a different TabBar or a different FlyoutItem
+					!shellSection.IsVisible || // user has set IsVisible on the ShellSection to false
+					this.Window is null; // user has set the main page to a different shell instance
+			}
+
+			if (!disconnect)
+			{
+				return;
+			}
+
+			if (_contentCache is not null)
+			{
+				_contentCache.Unloaded -= OnPageUnloaded;
+				RemoveLogicalChild(_contentCache);
+			}
+
+			_contentCache = null;
+		}
+
+		protected override void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberName] string propertyName = null)
+		{
+			base.OnPropertyChanged(propertyName);
+
+			if (propertyName == WindowProperty.PropertyName)
+			{
+				if(_contentCache?.IsLoaded == true)
+					return;
+
+				EvaluateDisconnect();
+			}
+		}
+
+		void OnPageUnloaded(object sender, EventArgs e) => EvaluateDisconnect();
+
 		public static implicit operator ShellContent(TemplatedPage page)
 		{
 			if (page.Parent != null)
@@ -223,6 +294,7 @@ public static implicit operator ShellContent(TemplatedPage page)
 		static void OnContentChanged(BindableObject bindable, object oldValue, object newValue)
 		{
 			var shellContent = (ShellContent)bindable;
+			shellContent._createdViaService = false;
 			// This check is wrong but will work for testing
 			if (shellContent.ContentTemplate == null)
 			{

src/Controls/tests/TestCases.HostApp/Issues/Shell/ShellTransientTests.cs

@@ -0,0 +1,139 @@
+using System;
+using System.Diagnostics;
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.None, 0, "Validate Basic Service Lifetime Behavior On Shell")]
+	public class ShellTransientTests : Shell
+	{
+        static List<ContentPage> _contentPages = new List<ContentPage>();
+		protected override void OnNavigated(ShellNavigatedEventArgs args)
+		{
+			base.OnNavigated(args);
+            LoadCurrentPage();
+		}
+
+        void LoadCurrentPage()
+        {
+            var navigatetoTransientPage = new Button 
+            { 
+                Text = "Navigate to transient page", 
+                AutomationId = "NavigateToTransientPage",
+                Command = new Command(() => 
+                {
+                    ((ContentPage)this.CurrentPage).Content = new Label(){ Text = "Navigating. If you tried to navigate to the same page type, you'll be stuck here."};
+                    this.CurrentItem = Items[0];
+                })
+            };
+
+            var navigateToNotRegisteredPage = new Button 
+            { 
+                Text = "Navigate to Unregistered page", 
+                AutomationId = "NavigateToUnregisteredPage",
+                Command = new Command(() => 
+                {
+                    ((ContentPage)this.CurrentPage).Content = new Label(){ Text = "Navigating. If you tried to navigate to the same page type, you'll be stuck here."};
+                    this.CurrentItem = Items[1];
+                })
+            };
+
+            var navigateToScopedPage = new Button 
+            { 
+                Text = "Navigate to scoped page", 
+                AutomationId = "NavigateToScopedPage",
+                Command = new Command(() => 
+                {
+                    ((ContentPage)this.CurrentPage).Content = new Label(){ Text = "Navigating. If you tried to navigate to the same page type, you'll be stuck here."};
+                    this.CurrentItem = Items[2];
+                })
+            };
+
+            var navigateToNewShell = new Button 
+            { 
+                Text = "Navigate to New Shell", 
+                AutomationId = "NavigateToNewShell",
+                Command = new Command(() => 
+                {
+                    this.Window.Page = new ShellTransientTests();
+                })
+            };
+
+            if (_contentPages.Contains(this.CurrentPage))
+            {
+                (CurrentPage as ContentPage).Content = new VerticalStackLayout()
+                {
+                    Children =
+                    {
+                        navigatetoTransientPage,
+                        navigateToNotRegisteredPage,
+                        navigateToScopedPage,
+                        navigateToNewShell,
+                        new Label { Text = "I am not a new page", AutomationId = "OldPage" }
+                    }
+                };
+            }
+            else
+            {
+                (CurrentPage as ContentPage).Content = new VerticalStackLayout()
+                {
+                    Children =
+                    {
+                        navigatetoTransientPage,
+                        navigateToNotRegisteredPage,
+                        navigateToScopedPage,
+                        navigateToNewShell,
+                        new Label { Text = "I am a new page", AutomationId = "NewPage" }
+                    }
+                };
+            }
+
+            _contentPages.Add((ContentPage)this.CurrentPage);
+        }
+
+		public ShellTransientTests()
+        {
+            var shellContent1 = new ShellContent()
+            {
+                ContentTemplate = new DataTemplate(typeof(TransientPage))
+            };
+
+            var shellContent2 = new ShellContent()
+            {
+                ContentTemplate = new DataTemplate(typeof(ContentPage))
+            };
+
+            var shellContent3 = new ShellContent()
+            {
+                ContentTemplate = new DataTemplate(typeof(ScopedPage))
+            };
+
+            Items.Add(new FlyoutItem()
+            {
+                Title = "Transient Page",
+                Items =
+                {
+                    shellContent1
+                }
+            });
+
+            Items.Add(new FlyoutItem()
+            {
+                Title = "Not Registered Page",
+                Items =
+                {
+                    shellContent2
+                }
+            });
+
+            Items.Add(new FlyoutItem()
+            {
+                Title = "Scoped Page",
+                Items =
+                {
+                    shellContent3
+                }
+            });
+        }
+	}
+}

src/Controls/tests/TestCases.HostApp/MauiProgram.cs

@@ -25,6 +25,8 @@ public static MauiApp CreateMauiApp()
 				})
 				.Issue21109AddMappers();
 
+			appBuilder.Services.AddTransient<TransientPage>();
+			appBuilder.Services.AddScoped<ScopedPage>();
 			return appBuilder.Build();
 		}
 	}

src/Controls/tests/TestCases.HostApp/ScopedPage.cs

@@ -0,0 +1,15 @@
+
+namespace Maui.Controls.Sample;
+
+public class ScopedPage : ContentPage
+{
+    static int i = 0;
+    public ScopedPage()
+    {
+        Index = i;
+        Content = new Label { Text = $"I'm a scoped page: {Index}" };
+        i++;
+    }
+
+    public int Index {get; private set;}
+}

src/Controls/tests/TestCases.HostApp/TransientPage.cs

@@ -0,0 +1,15 @@
+
+namespace Maui.Controls.Sample;
+
+public class TransientPage : ContentPage
+{
+    static int i = 0;
+    public TransientPage()
+    {
+        Index = i;
+        Content = new Label { Text = $"I'm a transient page: {Index}" };
+        i++;
+    }
+
+    public int Index {get; private set;}
+}