[iOS] Fix ScrollView does not resize when children are removed from StackLayout at runtime

src/Controls/tests/TestCases.HostApp/Issues/Issue32221.cs

@@ -0,0 +1,83 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 32221, "[iOS] ScrollView does not resize when children are removed from StackLayout at runtime", PlatformAffected.iOS)]
+
+public class Issue32221 : ContentPage
+{
+	int labelCount = 3;
+	StackLayout labelStack;
+
+	public Issue32221()
+	{
+		// Create the label stack
+		labelStack = new StackLayout
+		{
+			BackgroundColor = Colors.Beige,
+			Spacing = 10
+		};
+
+		// Add initial labels
+		for (int i = 1; i <= labelCount; i++)
+		{
+			labelStack.Children.Add(new Label
+			{
+				Text = $"Label {i}",
+				FontSize = 18,
+				Padding = new Thickness(10)
+			});
+		}
+
+		// Create ScrollView to hold the label stack
+		var scrollView = new ScrollView
+		{
+			Content = labelStack
+		};
+
+		// Create buttons
+		var addButton = new Button
+		{
+			Text = "Add Label",
+			AutomationId = "AddLabelButton"
+		};
+		addButton.Clicked += OnAddLabelClicked;
+
+		var removeButton = new Button
+		{
+			Text = "Remove Label",
+			AutomationId = "RemoveLabelButton"
+		};
+		removeButton.Clicked += OnRemoveLabelClicked;
+
+		// Create the main layout
+		var mainLayout = new VerticalStackLayout
+		{
+			Padding = 20,
+			Children = { scrollView, addButton, removeButton }
+		};
+
+		// Set the page content
+		Content = mainLayout;
+	}
+
+	void OnAddLabelClicked(object sender, EventArgs e)
+	{
+		labelCount++;
+		labelStack.Children.Add(new Label
+		{
+			Text = $"Label {labelCount}",
+			FontSize = 18,
+			Padding = new Thickness(10)
+		});
+	}
+
+	void OnRemoveLabelClicked(object sender, EventArgs e)
+	{
+		if (labelStack.Children.Count > 0)
+		{
+			labelStack.Children.RemoveAt(labelStack.Children.Count - 1);
+			labelCount--;
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue32221.cs

@@ -0,0 +1,20 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+public class Issue32221 : _IssuesUITest
+{
+	public Issue32221(TestDevice device) : base(device) { }
+
+	public override string Issue => "[iOS] ScrollView does not resize when children are removed from StackLayout at runtime";
+	[Test]
+	[Category(UITestCategories.ScrollView)]
+	public void VerifyScrollViewHeightWhenRemoveChildAtRuntime()
+	{
+		App.WaitForElement("AddLabelButton");
+		App.Tap("AddLabelButton");
+		App.Tap("RemoveLabelButton");
+		VerifyScreenshot();
+	}
+}

src/Core/src/Platform/iOS/MauiScrollView.cs

@@ -92,12 +92,12 @@ public override void LayoutSubviews()
 				if (ContentSize != contentSize)
 				{
 					ContentSize = contentSize;
-
-					// Invalidation stops at `UIScrollViews` for performance reasons,
-					// but when the content size changes, we need to invalidate the ancestors
-					// in case the ScrollView is configured to grow/shrink with its content.
-					this.InvalidateAncestorsMeasures();
 				}
+
+				// Invalidation stops at `UIScrollViews` for performance reasons,
+				// but when the content size changes, we need to invalidate the ancestors
+				// in case the ScrollView is configured to grow/shrink with its content.
+				this.InvalidateAncestorsMeasures();
 			}
 
 			base.LayoutSubviews();