[iOS] Fix for Incorrect Scroll in Loop Mode When CurrentItem Is Not Found in ItemsSource

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

@@ -459,6 +459,12 @@ internal void UpdateLoop()
 
 		void ScrollToPosition(int goToPosition, int carouselPosition, bool animate, bool forceScroll = false)
 		{
+			if (goToPosition < 0)
+			{
+				System.Diagnostics.Debug.WriteLine($"CarouselViewController.ScrollToPosition: Skipping scroll due to invalid goToPosition ({goToPosition})");
+				return;
+			}
+
 			if (ItemsView is not CarouselView carousel)
 			{
 				return;

src/Controls/src/Core/Handlers/Items2/iOS/CarouselViewController2.cs

@@ -387,6 +387,12 @@ internal void UpdateLoop()
 
 		void ScrollToPosition(int goToPosition, int carouselPosition, bool animate, bool forceScroll = false)
 		{
+			if (goToPosition < 0)
+			{
+				System.Diagnostics.Debug.WriteLine($"CarouselViewController2.ScrollToPosition: Skipping scroll due to invalid goToPosition ({goToPosition}).");
+				return;
+			}
+
 			if (ItemsView is not CarouselView carousel)
 			{
 				return;

src/Controls/tests/TestCases.HostApp/Issues/Issue32139.cs

@@ -0,0 +1,68 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 32139, "CarouselView scrolls to last item when Loop is enabled and CurrentItem is set to an item not in the list", PlatformAffected.iOS)]
+public class Issue32139 : ContentPage
+{
+	const string InitialItem = "0";
+	const string InvalidItem = "14";
+
+	Label selectedItemLabel;
+	CarouselView carouselView;
+	public Issue32139()
+	{
+		carouselView = new CarouselView
+		{
+			HeightRequest = 150,
+			Loop = true,
+			ItemsSource = new ObservableCollection<string> { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11" },
+			ItemTemplate = new DataTemplate(() =>
+			{
+				Border border = new Border
+				{
+					BackgroundColor = Colors.LightGray,
+					Content = new Label
+					{
+						VerticalOptions = LayoutOptions.Center,
+						HorizontalOptions = LayoutOptions.Center,
+						FontSize = 80
+					}
+				};
+				border.Content.SetBinding(Label.TextProperty, ".");
+				return border;
+			})
+		};
+
+		selectedItemLabel = new Label
+		{
+			Text = $"Selected Item : {InitialItem}",
+			FontSize = 16
+		};
+
+		Button selectButton = new Button
+		{
+			AutomationId = "Issue32139SelectBtn",
+			Text = $"Select item {InvalidItem}",
+			FontSize = 12
+		};
+
+		selectButton.Clicked += (s, e) =>
+		{
+			carouselView.CurrentItem = InvalidItem;
+			selectedItemLabel.Text = $"Selected Item : {carouselView.CurrentItem}";
+		};
+
+		Content = new VerticalStackLayout
+		{
+			Padding = 25,
+			Spacing = 15,
+			Children =
+			{
+				carouselView,
+				selectedItemLabel,
+				selectButton,
+			}
+		};
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue32139.cs

@@ -0,0 +1,26 @@
+#if TEST_FAILS_ON_WINDOWS && TEST_FAILS_ON_ANDROID // Related issues have been reported for both Android and Windows : Android (https://github.com/dotnet/maui/issues/29529) and Windows (https://github.com/dotnet/maui/issues/31670)
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue32139 : _IssuesUITest
+{
+	public Issue32139(TestDevice device) : base(device)
+	{
+	}
+
+	public override string Issue => "CarouselView scrolls to last item when Loop is enabled and CurrentItem is set to an item not in the list";
+
+	[Test]
+	[Category(UITestCategories.CarouselView)]
+	public void ValidateNoScrollOnInvalidItemWithLoop()
+	{
+		App.WaitForElement("Issue32139SelectBtn");
+		App.Tap("Issue32139SelectBtn");
+
+		VerifyScreenshot();
+	}
+}
+#endif