CollectionView Items display issue when Header is resized on iOS

src/Controls/src/Core/Handlers/Items/iOS/StructuredItemsViewController.cs

@@ -40,16 +40,6 @@ internal override void Disconnect()
 				_footerViewFormsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;
 			}
 
-			if (_headerUIView is MauiView hv)
-			{
-				hv.LayoutChanged -= HeaderViewLayoutChanged;
-			}
-
-			if (_footerUIView is MauiView fv)
-			{
-				fv.LayoutChanged -= FooterViewLayoutChanged;
-			}
-
 			_headerUIView = null;
 			_headerViewFormsElement = null;
 			_footerUIView = null;
@@ -125,36 +115,16 @@ public override void ViewWillLayoutSubviews()
 
 		internal void UpdateFooterView()
 		{
-			if (_footerUIView is MauiView mvPrevious)
-			{
-				mvPrevious.LayoutChanged -= FooterViewLayoutChanged;
-			}
-
 			UpdateSubview(ItemsView?.Footer, ItemsView?.FooterTemplate, FooterTag,
 				ref _footerUIView, ref _footerViewFormsElement);
 			UpdateHeaderFooterPosition();
-
-			if (_footerUIView is MauiView mv)
-			{
-				mv.LayoutChanged += FooterViewLayoutChanged;
-			}
 		}
 
 		internal void UpdateHeaderView()
 		{
-			if (_headerUIView is MauiView mvPrevious)
-			{
-				mvPrevious.LayoutChanged -= HeaderViewLayoutChanged;
-			}
-
 			UpdateSubview(ItemsView?.Header, ItemsView?.HeaderTemplate, HeaderTag,
 				ref _headerUIView, ref _headerViewFormsElement);
 			UpdateHeaderFooterPosition();
-
-			if (_headerUIView is MauiView mv)
-			{
-				mv.LayoutChanged += HeaderViewLayoutChanged;
-			}
 		}
 
 
@@ -200,8 +170,8 @@ void UpdateHeaderFooterPosition()
 			{
 				var currentInset = CollectionView.ContentInset;
 
-				nfloat headerWidth = _headerUIView?.Frame.Width ?? 0f;
-				nfloat footerWidth = _footerUIView?.Frame.Width ?? 0f;
+				nfloat headerWidth = _headerViewFormsElement?.ToPlatform()?.Frame.Width ?? 0f;
+				nfloat footerWidth = _footerViewFormsElement?.ToPlatform()?.Frame.Width ?? 0f;
 				nfloat emptyWidth = emptyView?.Frame.Width ?? 0f;
 
 				if (_headerUIView != null && _headerUIView.Frame.X != headerWidth)
@@ -230,8 +200,8 @@ void UpdateHeaderFooterPosition()
 			else
 			{
 				var currentInset = CollectionView.ContentInset;
-				nfloat headerHeight = _headerUIView?.Frame.Height ?? 0f;
-				nfloat footerHeight = _footerUIView?.Frame.Height ?? 0f;
+				nfloat headerHeight = _headerViewFormsElement?.ToPlatform()?.Frame.Height ?? 0f;
+				nfloat footerHeight = _footerViewFormsElement?.ToPlatform()?.Frame.Height ?? 0f;
 				nfloat emptyHeight = emptyView?.Frame.Height ?? 0f;
 
 				if (CollectionView.ContentInset.Top != headerHeight || CollectionView.ContentInset.Bottom != footerHeight)
@@ -283,15 +253,5 @@ internal void UpdateLayoutMeasurements()
 			if (_footerViewFormsElement != null)
 				HandleFormsElementMeasureInvalidated(_footerViewFormsElement);
 		}
-
-		void HeaderViewLayoutChanged(object sender, EventArgs e)
-		{
-			HandleFormsElementMeasureInvalidated(_headerViewFormsElement);
-		}
-
-		void FooterViewLayoutChanged(object sender, EventArgs e)
-		{
-			HandleFormsElementMeasureInvalidated(_footerViewFormsElement);
-		}
 	}
 }

src/Controls/tests/TestCases.HostApp/Issues/Issue25362.xaml

@@ -0,0 +1,43 @@
+<?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.Issue25362"
+             x:Name="Self"
+             Title="Issue25362">
+    <Grid RowDefinitions="Auto,*">
+        <HorizontalStackLayout Grid.Row="0">
+            <Button
+                Command="{Binding AddCommand}"
+                HorizontalOptions="Center"
+                AutomationId="button"
+                Text="Add" />
+        </HorizontalStackLayout>
+
+        <CollectionView
+            Grid.Row="1"
+            ItemsSource="{Binding ItemList}">
+
+            <CollectionView.Header>
+                <VerticalStackLayout>
+                    <VerticalStackLayout BindableLayout.ItemsSource="{Binding BindingContext.ItemListHeader, Source={x:Reference Self}}">
+                        <BindableLayout.ItemTemplate>
+                            <DataTemplate>
+                                <Label Padding="10" Text="{Binding .}" />
+                            </DataTemplate>
+                        </BindableLayout.ItemTemplate>
+                    </VerticalStackLayout>
+                    <BoxView
+                        Margin="0,5"
+                        HeightRequest="2"
+                        Color="Black" />
+                </VerticalStackLayout>
+            </CollectionView.Header>
+
+            <CollectionView.ItemTemplate>
+                <DataTemplate>
+                    <Label Padding="10" Text="{Binding .}" />
+                </DataTemplate>
+            </CollectionView.ItemTemplate>
+        </CollectionView>
+    </Grid>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue25362.xaml.cs

@@ -0,0 +1,24 @@
+using System.Collections.ObjectModel;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues;
+
+[XamlCompilation(XamlCompilationOptions.Compile)]
+[Issue(IssueTracker.Github, 25362, "[iOS] CollectionView Items display issue when Header is resized", PlatformAffected.iOS)]
+
+public partial class Issue25362 : ContentPage
+{
+	public ObservableCollection<string> ItemList { get; }
+	public ObservableCollection<string> ItemListHeader { get; }
+
+	public Command AddCommand => new(() => ItemListHeader.Add($"HeaderItem{ItemListHeader.Count + 1}"));
+
+	public Issue25362()
+	{
+		InitializeComponent();
+		ItemList = new() { "Item1", "Item2", "Itme3" };
+		ItemListHeader = new() { "HeaderItem1" };
+		BindingContext = this;
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25362.cs

@@ -0,0 +1,26 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue25362 : _IssuesUITest
+{
+	public override string Issue => "[iOS] CollectionView Items display issue when Header is resized";
+
+	public Issue25362(TestDevice device) : base(device)
+	{ }
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void HeaderShouldNotCollapseWithItems()
+	{
+		App.WaitForElement("button");
+		App.Click("button");
+		App.Click("button");
+		App.Click("button");
+
+		//The test passes of header has 4 elements that don't overlap with the collection view's items
+		VerifyScreenshot();
+	}
+}

src/Core/src/Platform/iOS/MauiView.cs

@@ -137,7 +137,6 @@ public override void LayoutSubviews()
 			}
 
 			CrossPlatformArrange(bounds);
-			OnLayoutChanged();
 		}
 
 		public override void SetNeedsLayout()
@@ -199,13 +198,5 @@ public override void MovedToWindow()
 			_movedToWindow?.Invoke(this, EventArgs.Empty);
 			TryToInvalidateSuperView(true);
 		}
-
-		[UnconditionalSuppressMessage("Memory", "MEM0001", Justification = IUIViewLifeCycleEvents.UnconditionalSuppressMessage)]
-		internal event EventHandler? LayoutChanged;
-
-		private void OnLayoutChanged()
-		{
-			LayoutChanged?.Invoke(this, EventArgs.Empty);
-		}
 	}
 }