[iOS] Added support for large titles in Shell (#32081)

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### Description of Change

Introduces the UpdateLargeTitles method to manage large title display
modes for navigation bars in ShellItemRenderer. This ensures that the
large title preference is updated when the displayed page changes or
when the view lays out subviews, aligning with iOS-specific platform
configurations.

### Issues Fixed

<!-- Please make sure that there is a bug logged for the issue being
fixed. The bug should describe the problem and how to reproduce it. -->

Fixes #12156

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Author: jfversluis

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

@@ -5,6 +5,7 @@
 using System.ComponentModel;
 using System.Linq;
 using Foundation;
+using Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;
 using Microsoft.Maui.Graphics;
 using ObjCRuntime;
 using UIKit;
@@ -399,6 +400,7 @@ void OnDisplayedPageChanged(Page page)
 			{
 				_displayedPage.PropertyChanged += OnDisplayedPagePropertyChanged;
 				UpdateTabBarHidden();
+				UpdateLargeTitles();
 			}
 		}
 
@@ -408,6 +410,31 @@ void OnDisplayedPagePropertyChanged(object sender, PropertyChangedEventArgs e)
 				UpdateTabBarHidden();
 		}
 
+
+		void UpdateLargeTitles()
+		{
+			var page = _displayedPage;
+			if (page is null || !OperatingSystem.IsIOSVersionAtLeast(11))
+				return;
+
+			var largeTitleDisplayMode = page.OnThisPlatform().LargeTitleDisplay();
+
+			if (SelectedViewController is UINavigationController navigationController)
+			{
+				navigationController.NavigationBar.PrefersLargeTitles = largeTitleDisplayMode == LargeTitleDisplayMode.Always;
+				var top = navigationController.TopViewController;
+				if (top is not null)
+				{
+					top.NavigationItem.LargeTitleDisplayMode = largeTitleDisplayMode switch
+					{
+						LargeTitleDisplayMode.Always => UINavigationItemLargeTitleDisplayMode.Always,
+						LargeTitleDisplayMode.Automatic => UINavigationItemLargeTitleDisplayMode.Automatic,
+						_ => UINavigationItemLargeTitleDisplayMode.Never
+					};
+				}
+			}
+		}
+
 		void RemoveRenderer(IShellSectionRenderer renderer)
 		{
 			if (_sectionRenderers.Remove(renderer.ViewController))
@@ -441,6 +468,7 @@ IShellSectionRenderer RendererForViewController(UIViewController viewController)
 		public override void ViewWillLayoutSubviews()
 		{
 			UpdateTabBarHidden();
+			UpdateLargeTitles();
 			base.ViewWillLayoutSubviews();
 		}
 

src/Controls/tests/TestCases.HostApp/Issues/Issue12156.xaml

@@ -0,0 +1,17 @@
+<?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"
+       xmlns:ios="clr-namespace:Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;assembly=Microsoft.Maui.Controls"
+       x:Class="Maui.Controls.Sample.Issues.Issue12156">
+
+    <ShellContent Title="Home">
+        <ContentPage ios:Page.LargeTitleDisplay="Always">
+            <Label
+                Text="Issue 12156"
+                AutomationId="Label"
+                VerticalOptions="Center"
+                HorizontalOptions="Center"/>
+        </ContentPage>
+    </ShellContent>
+
+</Shell>

src/Controls/tests/TestCases.HostApp/Issues/Issue12156.xaml.cs

@@ -0,0 +1,10 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 12156, "iOS Page.LargeTitleDisplay does not work on iOS", PlatformAffected.iOS)]
+public partial class Issue12156 : Shell
+{
+	public Issue12156()
+	{
+		InitializeComponent();
+	}
+}

src/Controls/tests/TestCases.Mac.Tests/snapshots/mac/LargeTitleDisplayWorks.png

@@ -0,0 +1,24 @@
+#if TEST_FAILS_ON_ANDROID && TEST_FAILS_ON_ANDROID && TEST_FAILS_ON_WINDOWS
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue12156 : _IssuesUITest
+{
+	public Issue12156(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "iOS Page.LargeTitleDisplay does not work on iOS";
+
+	[Test]
+	[Category(UITestCategories.TitleView)]
+	public void LargeTitleDisplayWorks()
+	{
+		App.WaitForElement("Label");
+		VerifyScreenshot();
+	}
+}
+#endif