[iOS] Fixed Collection View header and footer update

src/Controls/samples/Controls.Sample.UITests/Issues/Issue19379.xaml

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue19379"
+             xmlns:ns="clr-namespace:Maui.Controls.Sample.Issues">
+    <VerticalStackLayout 
+        Padding="30,0"
+        Spacing="25">
+        <Label 
+            AutomationId="WaitForStubControl"
+            Text="Issue 19379"/>
+        <CollectionView 
+            Header="{Binding CustomHeader, Mode=TwoWay}"       
+            ItemsSource="{Binding ItemList}">
+            <CollectionView.HeaderTemplate>
+                <DataTemplate>
+                    <ContentView>
+                        <Label 
+                            Text="{Binding Title}" 
+                            BackgroundColor="Yellow" 
+                            Margin="0,10"/>
+                    </ContentView>
+                </DataTemplate>
+            </CollectionView.HeaderTemplate>
+            <CollectionView.ItemTemplate>
+                <DataTemplate>
+                    <Label 
+                        Text="{Binding .}"
+                        BackgroundColor="SkyBlue"
+                        Margin="10"
+                        VerticalOptions="Center"
+                        VerticalTextAlignment="Center"/>
+                </DataTemplate>
+            </CollectionView.ItemTemplate>
+        </CollectionView>
+        <Button 
+            AutomationId="UpdateButton"
+            Text="Update the CollectionView header"
+            Clicked="Button_Clicked"/>
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample.UITests/Issues/Issue19379.xaml.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 19379, "Not able to update CollectionView header", PlatformAffected.iOS)]
+	public partial class Issue19379 : ContentPage
+	{
+		int _initValue; 
+		IList<string> _itemList;
+		Issue19379CustomHeader _customHeader;
+
+		public Issue19379()
+		{
+			InitializeComponent();
+			BindingContext = this;
+
+			PopulateList();
+			CustomHeader = new Issue19379CustomHeader
+			{
+				Title = "This is a CollectionViewHeader"
+			};
+		}
+
+		void Button_Clicked(object sender, EventArgs e)
+		{
+			_initValue++;
+			CustomHeader = new Issue19379CustomHeader
+			{
+				Title = $"This is a CollectionViewHeader #{_initValue}"
+			};
+		}
+
+		void PopulateList()
+		{
+			ItemList = new List<string>()
+			{
+				"This is an item",
+				"This is an item",
+				"This is an item",
+				"This is an item",
+				"This is an item",
+				"This is an item"
+			};
+		}
+
+		protected override void OnAppearing()
+		{
+			base.OnAppearing();
+		}
+
+
+
+		public IList<string> ItemList
+		{
+			get { return _itemList; }
+			set
+			{
+				_itemList = value;
+				OnPropertyChanged();
+			}
+		}
+
+		public Issue19379CustomHeader CustomHeader
+		{
+			get { return _customHeader; }
+			set
+			{
+				_customHeader = value;
+				OnPropertyChanged();
+			}
+		}
+	}
+
+	public class Issue19379CustomHeader
+	{
+		public string Title { get; set; }
+	}
+}

src/Controls/src/Core/Handlers/Items/CollectionViewHandler.cs

@@ -29,6 +29,8 @@ public CollectionViewHandler(PropertyMapper mapper = null) : base(mapper ?? Mapp
 			[Controls.ItemsView.IsVisibleProperty.PropertyName] = MapIsVisible,
 			[Controls.ItemsView.ItemsUpdatingScrollModeProperty.PropertyName] = MapItemsUpdatingScrollMode,
 			[StructuredItemsView.HeaderTemplateProperty.PropertyName] = MapHeaderTemplate,
+			[StructuredItemsView.HeaderProperty.PropertyName] = MapHeaderTemplate,
+			[StructuredItemsView.FooterProperty.PropertyName] = MapFooterTemplate,
 			[StructuredItemsView.FooterTemplateProperty.PropertyName] = MapFooterTemplate,
 			[StructuredItemsView.ItemsLayoutProperty.PropertyName] = MapItemsLayout,
 			[StructuredItemsView.ItemSizingStrategyProperty.PropertyName] = MapItemSizingStrategy,

src/Controls/tests/UITests/Tests/Issues/Issue19379.cs

@@ -0,0 +1,29 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.AppiumTests.Issues
+{
+	public class Issue19379 : _IssuesUITest
+	{
+		public Issue19379(TestDevice device)
+			: base(device)
+		{ }
+
+		public override string Issue => "Not able to update CollectionView header";
+
+		[Test]
+		public void UpdateCollectionViewHeaderTest()
+		{
+			this.IgnoreIfPlatforms(new TestDevice[] { TestDevice.Android, TestDevice.Mac, TestDevice.Windows });
+
+			App.WaitForElement("WaitForStubControl");
+
+			// 1. Update the CollectionView Header.
+			App.Click("UpdateButton");
+
+			// 2. Verify the result.
+			VerifyScreenshot();
+		}
+	}
+}