[iOS] Implement ScrollView Orientation

src/Controls/samples/Controls.Sample/Pages/Layouts/ScrollViewPages/ScrollViewOrientationPage.xaml

@@ -0,0 +1,33 @@
+<views:BasePage
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    x:Class="Maui.Controls.Sample.Pages.ScrollViewPages.ScrollViewOrientationPage"
+    xmlns:views="clr-namespace:Maui.Controls.Sample.Pages.Base"
+    Title="ScrollView">
+    <views:BasePage.Content>
+        <Grid Padding="12" ColumnSpacing="2">
+            <Grid.RowDefinitions>
+                <RowDefinition Height="Auto"/>
+                <RowDefinition />
+            </Grid.RowDefinitions>
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="Auto"/>
+                <ColumnDefinition/>
+            </Grid.ColumnDefinitions>
+            <Label Text="Change Orientation:"
+                   Style="{StaticResource Headline}" VerticalOptions="Center" />
+
+            <Picker x:Name="Orientation" Grid.Column="1" SelectedIndex="0" SelectedIndexChanged="OrientationSelectedIndexChanged" VerticalOptions="Start">
+                <Picker.Items>
+                    <x:String>Vertical</x:String>
+                    <x:String>Horizontal</x:String>
+                    <x:String>Both</x:String>
+                    <x:String>Neither</x:String>
+                </Picker.Items>
+            </Picker>
+            <ScrollView x:Name="ScrollViewer" Orientation="Horizontal" Grid.Row="1" Grid.ColumnSpan="2">
+                <Image Source="dotnet_bot.png" HeightRequest="1000" WidthRequest="1000" Aspect="AspectFit" />
+            </ScrollView>
+        </Grid>
+    </views:BasePage.Content>
+</views:BasePage>

src/Controls/samples/Controls.Sample/Pages/Layouts/ScrollViewPages/ScrollViewOrientationPage.xaml.cs

@@ -0,0 +1,26 @@
+using System;
+using Microsoft.Maui;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Graphics;
+
+namespace Maui.Controls.Sample.Pages.ScrollViewPages
+{
+	public partial class ScrollViewOrientationPage
+	{
+		public ScrollViewOrientationPage()
+		{
+			InitializeComponent();
+		}
+
+		public void OrientationSelectedIndexChanged(object sender, EventArgs args)
+		{
+			ScrollViewer.Orientation = (ScrollOrientation)Orientation.SelectedIndex;
+		}
+
+		protected override void OnAppearing()
+		{
+			Orientation.SelectedIndex = 0;
+			base.OnAppearing();
+		}
+	}
+}

src/Controls/samples/Controls.Sample/ViewModels/ScrollViewOptionsModel.cs

@@ -35,6 +35,10 @@ protected override IEnumerable<SectionModel> CreateItems() => new[]
 				new ScrollViewTemplatePageModel{ Spacing = 200, ScrollViewPadding = new Thickness(25),
 					ContentBackground = Colors.LightBlue, VerticalAlignment = LayoutOptions.Fill }),
 
+			new SectionModel(typeof(ScrollViewOrientationPage), "Orientation",
+				"Lock the orientation of your ScrollView",
+				new ScrollViewTemplatePageModel{ VerticalAlignment = LayoutOptions.Fill }),
+
 
 		};
 	}

src/Core/src/Handlers/ScrollView/ScrollViewHandler.iOS.cs

@@ -58,12 +58,12 @@ public static void MapContent(IScrollViewHandler handler, IScrollView scrollView
 		// We don't actually have this mapped because we don't need it, but we can't remove it because it's public
 		public static void MapContentSize(IScrollViewHandler handler, IScrollView scrollView)
 		{
-			handler.PlatformView.UpdateContentSize(scrollView.ContentSize);
+			handler.PlatformView?.UpdateContentSize(scrollView.ContentSize);
 		}
 
 		public static void MapIsEnabled(IScrollViewHandler handler, IScrollView scrollView)
 		{
-			handler.PlatformView.UpdateIsEnabled(scrollView);
+			handler.PlatformView?.UpdateIsEnabled(scrollView);
 		}
 
 		public static void MapHorizontalScrollBarVisibility(IScrollViewHandler handler, IScrollView scrollView)
@@ -78,7 +78,10 @@ public static void MapVerticalScrollBarVisibility(IScrollViewHandler handler, IS
 
 		public static void MapOrientation(IScrollViewHandler handler, IScrollView scrollView)
 		{
-			// Nothing to do here for now, but we might need to make adjustments for FlowDirection when the orientation is set to Horizontal
+			if (GetContentView(handler.PlatformView) is ContentView currentContentContainer)
+			{
+				currentContentContainer.SetNeedsLayout();
+			}
 		}
 
 		public static void MapRequestScrollTo(IScrollViewHandler handler, IScrollView scrollView, object? args)
@@ -155,35 +158,34 @@ static void InsertContentView(UIScrollView platformScrollView, IScrollView scrol
 				Tag = ContentPanelTag
 			};
 
-			contentContainer.CrossPlatformArrange = ArrangeScrollViewContent(scrollView.CrossPlatformArrange, contentContainer, platformScrollView);
+			contentContainer.CrossPlatformArrange = ArrangeScrollViewContent(scrollView.CrossPlatformArrange, contentContainer, platformScrollView, scrollView);
 
 			platformScrollView.ClearSubviews();
 			contentContainer.AddSubview(platformContent);
 			platformScrollView.AddSubview(contentContainer);
 		}
 
-		static Func<Rect, Size> ArrangeScrollViewContent(Func<Rect, Size> internalArrange, ContentView container, UIScrollView platformScrollView)
+		static Func<Rect, Size> ArrangeScrollViewContent(Func<Rect, Size> internalArrange, ContentView container, UIScrollView platformScrollView, IScrollView scrollView)
 		{
 			return (rect) =>
 			{
-				if (container.Superview is UIScrollView scrollView)
+				if (container.Superview is UIScrollView uiScrollView)
 				{
 					// Ensure the container is at least the size of the UIScrollView itself, so that the 
 					// cross-platform layout logic makes sense and the contents don't arrange outside the 
 					// container. (Everything will look correct if they do, but hit testing won't work properly.)
 
-					var scrollViewBounds = scrollView.Bounds;
+					var scrollViewBounds = uiScrollView.Bounds;
 					var containerBounds = container.Bounds;
 
 					container.Bounds = new CGRect(0, 0,
 						Math.Max(containerBounds.Width, scrollViewBounds.Width),
 						Math.Max(containerBounds.Height, scrollViewBounds.Height));
 					container.Center = new CGPoint(container.Bounds.GetMidX(), container.Bounds.GetMidY());
 				}
-
 				var contentSize = internalArrange(rect);
-				platformScrollView.ContentSize = contentSize;
-				return contentSize;
+				var size = SetContentSizeForOrientation(platformScrollView, scrollView.Orientation, contentSize);
+				return size;
 			};
 		}
 
@@ -241,13 +243,13 @@ public override Size GetDesiredSize(double widthConstraint, double heightConstra
 			widthConstraint = AccountForPadding(widthConstraint, padding.HorizontalThickness);
 			heightConstraint = AccountForPadding(heightConstraint, padding.VerticalThickness);
 
-			var size = virtualView.CrossPlatformMeasure(widthConstraint, heightConstraint);
+			var crossPlatformSize = virtualView.CrossPlatformMeasure(widthConstraint, heightConstraint);
 
 			// Add the padding back in for the final size
-			size.Width += padding.HorizontalThickness;
-			size.Height += padding.VerticalThickness;
+			crossPlatformSize.Width += padding.HorizontalThickness;
+			crossPlatformSize.Height += padding.VerticalThickness;
 
-			platformView.ContentSize = size;
+			var size = SetContentSizeForOrientation(platformView, virtualView.Orientation, crossPlatformSize);
 
 			var finalWidth = ViewHandlerExtensions.ResolveConstraints(size.Width, virtualView.Width, virtualView.MinimumWidth, virtualView.MaximumWidth);
 			var finalHeight = ViewHandlerExtensions.ResolveConstraints(size.Height, virtualView.Height, virtualView.MinimumHeight, virtualView.MaximumHeight);
@@ -286,5 +288,28 @@ static double AccountForPadding(double constraint, double padding)
 			// Remove the padding from the constraint, but don't allow it to go negative
 			return Math.Max(0, constraint - padding);
 		}
+
+		static Size SetContentSizeForOrientation(UIScrollView platformScrollView, ScrollOrientation orientation, Size crossPlatformSize)
+		{
+			CGRect scrollViewBounds = platformScrollView.Bounds;
+			var contentSize = AccountForOrientation(crossPlatformSize, scrollViewBounds.Width, scrollViewBounds.Height, orientation);
+			platformScrollView.ContentSize = contentSize;
+			return contentSize;
+		}
+
+		internal static Size AccountForOrientation(Size size, double widthConstraint, double heightConstraint, ScrollOrientation orientation)
+		{
+			if (orientation is ScrollOrientation.Vertical or ScrollOrientation.Neither)
+			{
+				size.Width = widthConstraint;
+			}
+
+			if (orientation is ScrollOrientation.Horizontal or ScrollOrientation.Neither)
+			{
+				size.Height = heightConstraint;
+			}
+
+			return size;
+		}
 	}
 }

src/Core/src/PublicAPI/net-ios/PublicAPI.Unshipped.txt

@@ -34,4 +34,4 @@ static Microsoft.Maui.Platform.WebViewExtensions.UpdateUserAgent(this WebKit.WKW
 Microsoft.Maui.WeakEventManager.HandleEvent(object? sender, object? args, string! eventName) -> void
 static Microsoft.Maui.SizeRequest.operator !=(Microsoft.Maui.SizeRequest left, Microsoft.Maui.SizeRequest right) -> bool
 static Microsoft.Maui.SizeRequest.operator ==(Microsoft.Maui.SizeRequest left, Microsoft.Maui.SizeRequest right) -> bool
-virtual Microsoft.Maui.MauiUIApplicationDelegate.PerformFetch(UIKit.UIApplication! application, System.Action<UIKit.UIBackgroundFetchResult>! completionHandler) -> void
+virtual Microsoft.Maui.MauiUIApplicationDelegate.PerformFetch(UIKit.UIApplication! application, System.Action<UIKit.UIBackgroundFetchResult>! completionHandler) -> void

src/Core/src/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt

@@ -34,4 +34,4 @@ Microsoft.Maui.WeakEventManager.HandleEvent(object? sender, object? args, string
 static Microsoft.Maui.SizeRequest.operator !=(Microsoft.Maui.SizeRequest left, Microsoft.Maui.SizeRequest right) -> bool
 static Microsoft.Maui.SizeRequest.operator ==(Microsoft.Maui.SizeRequest left, Microsoft.Maui.SizeRequest right) -> bool
 Microsoft.Maui.LifecycleEvents.iOSLifecycle.PerformFetch
-virtual Microsoft.Maui.MauiUIApplicationDelegate.PerformFetch(UIKit.UIApplication! application, System.Action<UIKit.UIBackgroundFetchResult>! completionHandler) -> void
+virtual Microsoft.Maui.MauiUIApplicationDelegate.PerformFetch(UIKit.UIApplication! application, System.Action<UIKit.UIBackgroundFetchResult>! completionHandler) -> void