[iOS] Fix CarouselView CurrentItem not updating with vertical LinearItemsLayout

src/Controls/samples/Controls.Sample.Sandbox/MainPage.xaml

@@ -2,4 +2,73 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              x:Class="Maui.Controls.Sample.MainPage"
              xmlns:local="clr-namespace:Maui.Controls.Sample">
+    <Grid Padding="20" RowSpacing="10">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="400"/>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto"/>
+        </Grid.RowDefinitions>
+
+        <!-- Title -->
+        <Label Grid.Row="0" 
+               Text="Vertical CarouselView Centering Test" 
+               FontSize="18" 
+               FontAttributes="Bold" 
+               HorizontalOptions="Center"/>
+
+        <!-- Handler info -->
+        <Label x:Name="HandlerLabel"
+               Grid.Row="1" 
+               Text="Handler: Unknown" 
+               FontSize="14" 
+               HorizontalOptions="Center"/>
+
+        <!-- CarouselView with Vertical Orientation -->
+        <CarouselView x:Name="TestCarouselView"
+                      Grid.Row="2"
+                      BackgroundColor="LightGray"
+                      Loop="True">
+            <CarouselView.ItemsLayout>
+                <LinearItemsLayout Orientation="Vertical"/>
+            </CarouselView.ItemsLayout>
+            <CarouselView.ItemTemplate>
+                <DataTemplate>
+                    <Grid BackgroundColor="LightBlue" Padding="20">
+                        <Label Text="{Binding}" 
+                               FontSize="24" 
+                               FontAttributes="Bold"
+                               HorizontalOptions="Center" 
+                               VerticalOptions="Center"/>
+                    </Grid>
+                </DataTemplate>
+            </CarouselView.ItemTemplate>
+        </CarouselView>
+
+        <!-- Current Item Display -->
+        <Label x:Name="CurrentItemLabel" 
+               AutomationId="CurrentItemLabel"
+               Grid.Row="3" 
+               Text="CurrentItem: (waiting...)" 
+               FontSize="16" 
+               FontAttributes="Bold"
+               HorizontalOptions="Center"/>
+
+        <!-- Instructions -->
+        <Label Grid.Row="4"
+               Text="Loop=True - Test scrolling past last item"
+               FontSize="12"
+               HorizontalOptions="Center"
+               TextColor="Gray"/>
+
+        <!-- Scroll Button -->
+        <Button x:Name="ScrollButton" 
+                AutomationId="ScrollButton"
+                Grid.Row="5" 
+                Text="Scroll to Next Item" 
+                Clicked="OnScrollButtonClicked"
+                HorizontalOptions="Center"/>
+    </Grid>
 </ContentPage>

src/Controls/samples/Controls.Sample.Sandbox/MainPage.xaml.cs

@@ -1,9 +1,111 @@
-namespace Maui.Controls.Sample;
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample;
 
 public partial class MainPage : ContentPage
 {
+	private ObservableCollection<string> _items;
+	private int _scrollCount = 0;
+
 	public MainPage()
 	{
 		InitializeComponent();
+
+		// Initialize data source
+		_items = new ObservableCollection<string>
+		{
+			"Item 1: Baboon",
+			"Item 2: Capuchin Monkey",
+			"Item 3: Blue Monkey",
+			"Item 4: Squirrel Monkey",
+			"Item 5: Golden Lion Tamarin"
+		};
+
+		TestCarouselView.ItemsSource = _items;
+		TestCarouselView.CurrentItem = _items[0];
+
+		// Subscribe to CurrentItemChanged event
+		TestCarouselView.CurrentItemChanged += OnCurrentItemChanged;
+
+		// Display handler info after layout
+		TestCarouselView.Loaded += (s, e) =>
+		{
+			var handlerType = TestCarouselView.Handler?.GetType().Name ?? "Unknown";
+			HandlerLabel.Text = $"Handler: {handlerType}";
+
+			Console.WriteLine("========== VERTICAL CAROUSELVIEW CENTERING TEST ==========");
+			Console.WriteLine($"Handler Type: {handlerType}");
+			Console.WriteLine($"Initial CurrentItem: {TestCarouselView.CurrentItem}");
+			Console.WriteLine($"Initial Position: {TestCarouselView.Position}");
+			Console.WriteLine($"Total Items: {_items.Count}");
+			Console.WriteLine($"Orientation: Vertical");
+			Console.WriteLine($"Loop: {TestCarouselView.Loop}");
+			Console.WriteLine("");
+			Console.WriteLine("INSTRUCTIONS:");
+			Console.WriteLine("1. Tap 'Scroll to Next Item' button repeatedly");
+			Console.WriteLine("2. Test scrolling past last item (Item 5) to see if it loops to Item 1");
+			Console.WriteLine("3. Watch CurrentItem updates in loop scenario");
+			Console.WriteLine("==========================================================");
+		};
+	}
+
+	private void OnScrollButtonClicked(object sender, EventArgs e)
+	{
+		_scrollCount++;
+		var targetIndex = _scrollCount % _items.Count;
+
+		Console.WriteLine("");
+		Console.WriteLine($"========== SCROLL #{_scrollCount} ==========");
+		Console.WriteLine($"Current Position: {TestCarouselView.Position}");
+		Console.WriteLine($"Current Item: {TestCarouselView.CurrentItem}");
+		Console.WriteLine($"Scrolling to index: {targetIndex} ({_items[targetIndex]})");
+
+		if (_scrollCount > _items.Count)
+		{
+			Console.WriteLine("⚠️ TESTING LOOP BEHAVIOR - scrolling past end of collection");
+		}
+
+		TestCarouselView.ScrollTo(targetIndex, position: ScrollToPosition.Center, animate: true);
+
+		// Wait for scroll animation and log results
+		Task.Run(async () =>
+		{
+			await Task.Delay(1500);
+			MainThread.BeginInvokeOnMainThread(() =>
+			{
+				Console.WriteLine($"After scroll - Position: {TestCarouselView.Position}, CurrentItem: {TestCarouselView.CurrentItem}");
+
+				if (TestCarouselView.CurrentItem?.ToString() == _items[targetIndex])
+				{
+					Console.WriteLine("✅ CurrentItem updated correctly");
+				}
+				else
+				{
+					Console.WriteLine($"❌ CurrentItem mismatch! Expected: {_items[targetIndex]}, Got: {TestCarouselView.CurrentItem}");
+				}
+				Console.WriteLine("==========================================");
+			});
+		});
+	}
+
+	private void OnCurrentItemChanged(object? sender, CurrentItemChangedEventArgs e)
+	{
+		Console.WriteLine("");
+		Console.WriteLine("========== CurrentItemChanged EVENT ==========");
+		Console.WriteLine($"Previous: {e.PreviousItem ?? "null"}");
+		Console.WriteLine($"Current: {e.CurrentItem ?? "null"}");
+		Console.WriteLine($"Position: {TestCarouselView.Position}");
+		Console.WriteLine("==============================================");
+
+		if (e.CurrentItem != null)
+		{
+			CurrentItemLabel.Text = $"CurrentItem: {e.CurrentItem}";
+			Console.WriteLine($"✅ CurrentItem updated to: {e.CurrentItem}");
+		}
+		else
+		{
+			CurrentItemLabel.Text = "CurrentItem: (null)";
+			Console.WriteLine("⚠️ WARNING: CurrentItem is null");
+		}
 	}
 }

src/Controls/samples/Controls.Sample.Sandbox/MauiProgram.cs

@@ -1,14 +1,34 @@
-namespace Maui.Controls.Sample;
+namespace Maui.Controls.Sample;
 
 public static class MauiProgram
 {
+	// Toggle this to test different handlers
+	// true = Use Handler2 (CURRENT DEFAULT - the one being fixed in PR)
+	// false = Use Handler1 (LEGACY - to compare behavior)
+	private static bool UseHandler2 = true;
+
 	public static MauiApp CreateMauiApp() =>
 		MauiApp
 			.CreateBuilder()
 #if __ANDROID__ || __IOS__
 			.UseMauiMaps()
 #endif
 			.UseMauiApp<App>()
+			.ConfigureMauiHandlers(handlers =>
+			{
+#if IOS || MACCATALYST
+				if (!UseHandler2)
+				{
+					// Force use of legacy Handler1 by overriding default
+					handlers.AddHandler<Microsoft.Maui.Controls.CarouselView, Microsoft.Maui.Controls.Handlers.Items.CarouselViewHandler>();
+					Console.WriteLine("✅ Forcing CarouselViewHandler1 (legacy)");
+				}
+				else
+				{
+					Console.WriteLine("✅ Using CarouselViewHandler2 (current default)");
+				}
+#endif
+			})
 			.ConfigureFonts(fonts =>
 			{
 				fonts.AddFont("Dokdo-Regular.ttf", "Dokdo");

src/Controls/src/Core/Handlers/Items2/iOS/LayoutFactory2.cs

@@ -361,23 +361,24 @@ public static UICollectionViewLayout CreateCarouselLayout(
 					return;
 				}
 
-				// Calculate page index accounting for ItemSpacing
+				// Calculate page index accounting for ItemSpacing on the active axis.
 				var itemSpacing = itemsView.ItemsLayout is LinearItemsLayout linearLayout ? linearLayout.ItemSpacing : 0;
+				var effectivePageSize = (isHorizontal
+					? env.Container.ContentSize.Width
+					: env.Container.ContentSize.Height) - sectionMargin * 2 + itemSpacing;
 
-				var effectiveItemWidth = env.Container.ContentSize.Width - sectionMargin * 2 + itemSpacing;
-
-				if (effectiveItemWidth <= 0)
+				if (effectivePageSize <= 0)
 				{
 					return;
 				}
 
 				var pageOffset = isHorizontal ? offset.X : offset.Y;
-				var pageSize = isHorizontal
-					? env.Container.ContentSize.Width
-					: env.Container.ContentSize.Height;
-				double page = (pageOffset + sectionMargin) / effectiveItemWidth;
+				double page = (pageOffset + sectionMargin) / effectivePageSize;
 
-				if (Math.Abs(page % 1) > (double.Epsilon * 100) || cv2Controller.ItemsSource.ItemCount <= 0)
+				// Vertical: Scroll stops wherever touch is released (no auto-centering), so use 0.1 (10%) threshold
+				//           to accept positions near page boundaries where scroll naturally settles
+				double pageThreshold = isHorizontal ? (double.Epsilon * 100) : 0.1;
+				if (Math.Abs(page % 1) > pageThreshold || cv2Controller.ItemsSource.ItemCount <= 0)
 				{
 					return;
 				}

src/Controls/tests/TestCases.HostApp/Issues/Issue32136.cs

@@ -0,0 +1,76 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 32136, "CarouselView CurrentItem Not Updating with Vertical LinearItemsLayout", PlatformAffected.iOS)]
+public class Issue32136 : ContentPage
+{
+    public Issue32136()
+    {
+        CarouselView2 carouselView = new CarouselView2
+        {
+            HeightRequest = 400,
+            Loop = false,
+            BackgroundColor = Colors.LightGray,
+            AutomationId = "TestCarouselView",
+            ItemsLayout = new LinearItemsLayout(ItemsLayoutOrientation.Vertical),
+            ItemTemplate = new DataTemplate(() =>
+            {
+                Label label = new Label
+                {
+                    HorizontalOptions = LayoutOptions.Center,
+                    VerticalOptions = LayoutOptions.Center
+                };
+                label.SetBinding(Label.TextProperty, ".");
+
+                return new Grid
+                {
+                    Children = { label }
+                };
+            }),
+            ItemsSource = new string[]
+            {
+                "Baboon",
+                "Capuchin Monkey",
+                "Blue Monkey",
+                "Squirrel Monkey",
+                "Golden Lion Tamarin"
+            }
+        };
+
+        Label currentItemLabel = new Label();
+        currentItemLabel.AutomationId = "CurrentItemLabel";
+        currentItemLabel.Text = "CurrentItem = Baboon";
+
+        Button button = new Button
+        {
+            Text = "Next Item",
+            AutomationId = "ScrollButton"
+        };
+        button.Clicked += (s, e) =>
+        {
+            currentItemLabel.Text = "Button was clicked";
+            carouselView.ScrollTo(carouselView.Position + 1, position: ScrollToPosition.Center, animate: true);
+        };
+
+        carouselView.CurrentItemChanged += (s, e) =>
+        {
+            currentItemLabel.Text = $"CurrentItem = {e.CurrentItem}";
+        };
+
+        Grid grid = new Grid
+        {
+            Padding = 25,
+            RowSpacing = 10,
+            RowDefinitions =
+            {
+                new RowDefinition(GridLength.Auto),
+                new RowDefinition(GridLength.Auto),
+                new RowDefinition(GridLength.Auto)
+            }
+        };
+
+        grid.Add(carouselView);
+        grid.Add(currentItemLabel, row: 1);
+        grid.Add(button, row: 2);
+        Content = grid;
+    }
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue32136.cs

@@ -0,0 +1,24 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue32136 : _IssuesUITest
+{
+    public Issue32136(TestDevice device) : base(device)
+    {
+    }
+
+    public override string Issue => "CarouselView CurrentItem Not Updating with Vertical LinearItemsLayout";
+
+    [Test]
+    [Category(UITestCategories.CarouselView)]
+    public void CurrentItemShouldUpdateWhenScrollingVerticalCarouselView()
+    {
+        App.WaitForElement("ScrollButton");
+        App.Tap("ScrollButton");
+        var currentItemText = App.WaitForElement("CurrentItemLabel").GetText();
+        Assert.That(currentItemText, Is.EqualTo("CurrentItem = Capuchin Monkey"));
+    }
+}