[iOS] Fix ShellContent Title Does Not Update at Runtime

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellSectionRootHeader.cs

@@ -200,6 +200,10 @@ public override void ViewDidLoad()
 
 			UpdateSelectedIndex();
 			ShellSection.PropertyChanged += OnShellSectionPropertyChanged;
+			foreach (var shellContent in ShellSectionController.GetItems())
+			{
+				shellContent.PropertyChanged += OnShellContentPropertyChanged;
+			}
 		}
 
 		protected virtual Type GetCellType()
@@ -217,6 +221,10 @@ protected override void Dispose(bool disposing)
 				((IShellController)_shellContext.Shell).RemoveAppearanceObserver(this);
 				ShellSectionController.ItemsCollectionChanged -= OnShellSectionItemsChanged;
 				ShellSection.PropertyChanged -= OnShellSectionPropertyChanged;
+				foreach (var shellContent in ShellSectionController.GetItems())
+				{
+					shellContent.PropertyChanged -= OnShellContentPropertyChanged;
+				}
 
 				ShellSection = null;
 				_bar.RemoveFromSuperview();
@@ -279,9 +287,53 @@ protected virtual void UpdateSelectedIndex(bool animated = false)
 
 		void OnShellSectionItemsChanged(object sender, NotifyCollectionChangedEventArgs e)
 		{
+			HandleEventsOnItemsChange(e);
 			ReloadData();
 		}
 
+		void HandleEventsOnItemsChange(NotifyCollectionChangedEventArgs e)
+		{
+			if (e.OldItems != null)
+			{
+				foreach (ShellContent item in e.OldItems)
+				{
+					item.PropertyChanged -= OnShellContentPropertyChanged;
+				}
+			}
+
+			if (e.NewItems != null)
+			{
+				foreach (ShellContent item in e.NewItems)
+				{
+					item.PropertyChanged += OnShellContentPropertyChanged;
+				}
+			}
+		}
+
+		void OnShellContentPropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+			if (e.PropertyName == nameof(ShellContent.Title))
+			{
+				if (sender is ShellContent shellContent)
+				{
+					int index = ShellSectionController.GetItems().IndexOf(shellContent);
+					if (index >= 0)
+					{
+						UpdateHeaderTitle(index, shellContent);
+					}
+				}
+			}
+		}
+
+		void UpdateHeaderTitle(int index, ShellContent shellContent)
+		{
+			if (CollectionView.CellForItem(NSIndexPath.FromItemSection(index, 0)) is ShellSectionHeaderCell cell)
+			{
+				cell.Label.Text = shellContent.Title;
+				CollectionView.CollectionViewLayout.InvalidateLayout();
+			}
+		}
+
 		void ReloadData()
 		{
 			if (_isDisposed)

src/Controls/tests/TestCases.HostApp/Issues/Issue26049.xaml

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue26049"
+             FlyoutBehavior="Disabled"
+             Title="Issue26049">
+    <TabBar AutomationId="TabBar">
+    <Tab Title="Nested Tabs" x:Name="tabs" AutomationId="tabbar">
+        <ShellContent x:Name="tab1" Title="Home">
+            <ContentPage>
+                <StackLayout HorizontalOptions="Center" Spacing="20">
+
+                    <HorizontalStackLayout>
+                        <Label Text="Current Shell Title: " FontAttributes="Bold"/>
+                        <Label Text="{Binding Source={x:Reference tab1}, Path=Title}" AutomationId="FirstTabLabel"/>
+                    </HorizontalStackLayout>
+
+                    <HorizontalStackLayout>
+                        <Label Text="New Tab Title: " FontAttributes="Bold"/>
+                        <Label x:Name="newTabTitleLabel" AutomationId="NewTabTitleLabel"/>
+                    </HorizontalStackLayout>
+
+                    <HorizontalStackLayout>
+                        <Label Text="Third Tab Title: " FontAttributes="Bold"/>
+                        <Label x:Name="thirdTabTitleLabel" Text="{Binding Source={x:Reference tab3}, Path=Title}" AutomationId="ThirdTabTitleLabel"/>
+                    </HorizontalStackLayout>
+
+                    <Button Text="Change Title" AutomationId="ChangeShellContentTitle" VerticalOptions="Center" HorizontalOptions="Center" WidthRequest="150" HeightRequest="40" Clicked="OnButtonClicked"/>
+
+                    <Button Text="Add New Tab" AutomationId="AddShellContent"
+                            Clicked="OnAddShellContentClicked"/>
+
+                    <Button Text="Update New Tab Title" AutomationId="UpdateNewShellContentTitle"
+                            Clicked="OnUpdateNewShellContentTitleClicked"/>
+
+                    <Button Text="Remove New Tab" AutomationId="RemoveShellContent"
+                            Clicked="OnRemoveShellContentClicked"/>
+
+                    <Button Text="Update Third Tab Title" AutomationId="UpdateThirdTabTitle"
+                            Clicked="OnUpdateThirdTabTitleClicked"/>
+
+                </StackLayout>
+            </ContentPage>
+        </ShellContent>
+
+        <ShellContent x:Name="tab2" Title="Settings">
+            <ContentPage>
+                <Label Text="This is Settings page"/>
+            </ContentPage>
+        </ShellContent>
+
+        <ShellContent x:Name="tab3" Title="Profile">
+            <ContentPage>
+                <Label Text="This is Profile page"/>
+            </ContentPage>
+        </ShellContent>
+    </Tab>
+</TabBar>
+
+</Shell>

src/Controls/tests/TestCases.HostApp/Issues/Issue26049.xaml.cs

@@ -0,0 +1,65 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 26049, "[iOS] Fix ShellContent Title Does Not Update at Runtime", PlatformAffected.iOS | PlatformAffected.macOS)]
+public partial class Issue26049 : Shell
+{
+    ShellContent _dynamicShellContent;
+
+    public Issue26049()
+    {
+        InitializeComponent();
+    }
+
+	void OnButtonClicked(object sender, EventArgs e)
+	{
+		this.tab1.Title = "Updated";
+	}
+
+    void OnAddShellContentClicked(object sender, EventArgs e)
+    {
+        if (_dynamicShellContent == null)
+        {
+            _dynamicShellContent = new ShellContent
+            {
+                Title = "New Tab",
+                Content = new ContentPage
+                {
+                    Content = new Label { Text = "This is a dynamically added tab." }
+                }
+            };
+
+            this.tabs.Items.Add(_dynamicShellContent);
+            UpdateNewTabTitleLabel();
+        }
+    }
+
+    void OnUpdateNewShellContentTitleClicked(object sender, EventArgs e)
+    {
+        if (_dynamicShellContent != null)
+        {
+            _dynamicShellContent.Title = "Updated Title";
+            UpdateNewTabTitleLabel();
+        }
+    }
+
+    void OnRemoveShellContentClicked(object sender, EventArgs e)
+    {
+        if (_dynamicShellContent != null)
+        {
+            this.tabs.Items.Remove(_dynamicShellContent);
+            _dynamicShellContent = null;
+            newTabTitleLabel.Text = "";
+        }
+    }
+
+    void OnUpdateThirdTabTitleClicked(object sender, EventArgs e)
+    {
+        this.tab3.Title = "Updated Profile";
+        thirdTabTitleLabel.Text = this.tab3.Title;
+    }
+
+    void UpdateNewTabTitleLabel()
+    {
+        newTabTitleLabel.Text = _dynamicShellContent?.Title;
+    }
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue26049.cs

@@ -0,0 +1,46 @@
+#if TEST_FAILS_ON_ANDROID && TEST_FAILS_ON_WINDOWS   //More information - https://github.com/dotnet/maui/issues/27494
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue26049 : _IssuesUITest
+	{
+		public Issue26049(TestDevice device) : base(device)
+		{
+		}
+
+		public override string Issue => "[iOS] Fix ShellContent Title Does Not Update at Runtime";
+
+		[Test, Order(1)]
+		[Category(UITestCategories.Shell)]
+		public void VerifyFirstShellContentTitle()
+		{
+			App.WaitForElement("ChangeShellContentTitle");
+			App.Click("ChangeShellContentTitle");
+			VerifyScreenshot();
+		}
+
+		[Test, Order(2)]
+		[Category(UITestCategories.Shell)]
+		public void VerifyNewlyAddedShellContentTitle()
+		{
+			App.WaitForElement("AddShellContent");
+			App.Click("AddShellContent");
+			App.Click("UpdateNewShellContentTitle");
+			VerifyScreenshot();
+		}
+
+		[Test, Order(3)]
+		[Category(UITestCategories.Shell)]
+		public void VerifyExistingTabTitle()
+		{
+			App.WaitForElement("RemoveShellContent");
+			App.Click("RemoveShellContent");
+			App.Click("UpdateThirdTabTitle");
+			VerifyScreenshot();
+		}
+	}
+}
+#endif