[MacCatalyst] Fix CollectionView Header/Footer Not Expanding to Content Width

src/Controls/src/Core/Handlers/Items2/iOS/GroupableItemsViewController2.cs

@@ -102,6 +102,7 @@ public override UICollectionReusableView GetViewForSupplementaryElement(UICollec
 					UpdateDefaultSupplementaryView(DefaultCell2, elementKind, indexPath);
 					break;
 				case TemplatedCell2 TemplatedCell2:
+					TemplatedCell2.ScrollDirection = ScrollDirection;
 					UpdateTemplatedSupplementaryView(TemplatedCell2, elementKind, indexPath);
 					break;
 			}

src/Controls/src/Core/Handlers/Items2/iOS/StructuredItemsViewController2.cs

@@ -86,6 +86,7 @@ public override UICollectionReusableView GetViewForSupplementaryElement(UICollec
 					UpdateDefaultSupplementaryView(defaultCell, elementKind);
 					break;
 				case TemplatedCell2 templatedCell:
+					templatedCell.ScrollDirection = ScrollDirection;
 					UpdateTemplatedSupplementaryView(templatedCell, elementKind);
 					break;
 			}

src/Controls/tests/TestCases.HostApp/Issues/Issue35113.cs

@@ -0,0 +1,50 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 35113, "CV2 header/footer view width is not expanded to its content width on iOS/macOS", PlatformAffected.iOS | PlatformAffected.macOS)]
+public class Issue35113 : ContentPage
+{
+	public Issue35113()
+	{
+		var items = new ObservableCollection<string>();
+		for (int i = 0; i < 2; i++)
+			items.Add($"Item {i}");
+
+		// Header label with no explicit WidthRequest so it must self-size to its content width.
+		// With the bug: ScrollDirection defaults to Vertical on the supplementary TemplatedCell2.
+		// GetMeasureConstraints() constrains width to preferredAttributes.Size.Width (~30pt from
+		// LayoutFactory2's estimated value). The label text is clipped/invisible at 30pt and
+		// is absent from the accessibility tree — WaitForElement times out.
+		// With the fix: ScrollDirection = Horizontal is set, width is unconstrained, the label
+		// expands to its full content width and becomes accessible in the UI tree.
+		Content = new CollectionView2
+		{
+			ItemsLayout = new GridItemsLayout(3, ItemsLayoutOrientation.Horizontal),
+			Header = new Label
+			{
+				Text = "This Is A Header",
+				AutomationId = "Issue35113Header",
+				BackgroundColor = Colors.LightBlue,
+				FontSize = 24,
+				Padding = new Thickness(8),
+			},
+			Footer = new Label
+			{
+				Text = "This Is A Footer",
+				AutomationId = "Issue35113Footer",
+				BackgroundColor = Colors.LightGreen,
+				FontSize = 24,
+				Padding = new Thickness(8),
+			},
+			ItemTemplate = new DataTemplate(() =>
+			{
+				var label = new Label { Padding = 8 };
+				label.SetBinding(Label.TextProperty, ".");
+				return new Border { Content = label, Padding = 4 };
+			}),
+			ItemsSource = items,
+			AutomationId = "Issue35113CollectionView",
+		};
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue35113.cs

@@ -0,0 +1,42 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue35113 : _IssuesUITest
+{
+	public override string Issue => "CV2 header/footer view width is not expanded to its content width on iOS/macOS";
+
+	public Issue35113(TestDevice device) : base(device) { }
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void HorizontalGridHeaderExpandsToContentWidth()
+	{
+		// With the bug: the header's supplementary cell is constrained to ~30pt wide
+		// (LayoutFactory2 estimated value) because ScrollDirection is never set on
+		// TemplatedCell2. The header Label "This Is A Header" at FontSize=24 wraps
+		// into a narrow column — GetRect().Width should be near 30pt.
+		// With the fix: ScrollDirection is set correctly, the header self-sizes to
+		// content width — GetRect().Width should be well over 100pt.
+		App.WaitForElement("Issue35113Header");
+		var rect = App.FindElement("Issue35113Header").GetRect();
+		Assert.That(rect.Width, Is.GreaterThan(100),
+			$"Header width {rect.Width} should be > 100 when fully expanded. " +
+			"If ~30, ScrollDirection was not set on the supplementary TemplatedCell2.");
+	}
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void HorizontalGridFooterExpandsToContentWidth()
+	{
+		App.WaitForElement("Issue35113CollectionView");
+		App.ScrollTo("Issue35113Footer");
+		App.WaitForElement("Issue35113Footer");
+		var rect = App.FindElement("Issue35113Footer").GetRect();
+		Assert.That(rect.Width, Is.GreaterThan(100),
+			$"Footer width {rect.Width} should be > 100 when fully expanded. " +
+			"If ~30, ScrollDirection was not set on the supplementary TemplatedCell2.");
+	}
+}