[iOS/Catalyst] Correctly render ContentPage brushes background

src/Controls/samples/Controls.Sample/Pages/Core/ContentPageGalleries/ContentPageBackgroundGallery.xaml

@@ -0,0 +1,24 @@
+<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.ContentPageBackgroundGallery"
+    xmlns:views="clr-namespace:Maui.Controls.Sample.Pages.Base"
+    Title="ContentPage Background">
+    <ContentPage.Background>
+        <!-- StartPoint defaults to (0,0) -->
+        <LinearGradientBrush EndPoint="1,0">
+            <GradientStop Color="Yellow"   
+                          Offset="0.1" />
+            <GradientStop Color="Green"
+                          Offset="1.0" />
+        </LinearGradientBrush>
+    </ContentPage.Background>
+    <views:BasePage.Content>
+        <StackLayout>
+            <Label 
+                Text="ContentPage"
+                VerticalOptions="Center" 
+                HorizontalOptions="Center" />
+        </StackLayout>
+    </views:BasePage.Content>
+</views:BasePage>

src/Controls/samples/Controls.Sample/Pages/Core/ContentPageGalleries/ContentPageBackgroundGallery.xaml.cs

@@ -0,0 +1,10 @@
+namespace Maui.Controls.Sample.Pages
+{
+	public partial class ContentPageBackgroundGallery
+	{
+		public ContentPageBackgroundGallery()
+		{
+			InitializeComponent();
+		}
+	}
+}

src/Controls/samples/Controls.Sample/Pages/Core/ContentPageGallery.xaml → src/Controls/samples/Controls.Sample/Pages/Core/ContentPageGalleries/ContentPageBackgroundImageGallery.xaml

@@ -1,16 +1,16 @@
 <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.ContentPageGallery"
+    x:Class="Maui.Controls.Sample.Pages.ContentPageBackgroundImageGallery"
     xmlns:views="clr-namespace:Maui.Controls.Sample.Pages.Base"
-    Title="ContentPage Gallery"
+    Title="ContentPage BackgroundImage"
     BackgroundImageSource="oasis.jpg">
     <views:BasePage.Content>
         <StackLayout>
             <Label 
-            Text="ContentPage"
-            VerticalOptions="Center" 
-            HorizontalOptions="Center" />
+                Text="ContentPage"
+                VerticalOptions="Center" 
+                HorizontalOptions="Center" />
         </StackLayout>
     </views:BasePage.Content>
 </views:BasePage>

src/Controls/samples/Controls.Sample/Pages/Core/ContentPageGalleries/ContentPageBackgroundImageGallery.xaml.cs

@@ -0,0 +1,10 @@
+namespace Maui.Controls.Sample.Pages
+{
+	public partial class ContentPageBackgroundImageGallery
+	{
+		public ContentPageBackgroundImageGallery()
+		{
+			InitializeComponent();
+		}
+	}
+}

src/Controls/samples/Controls.Sample/Pages/Core/ContentPageGalleries/ContentPageGallery.cs

@@ -0,0 +1,33 @@
+using Microsoft.Maui;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Internals;
+
+namespace Maui.Controls.Sample.Pages
+{
+	[Preserve(AllMembers = true)]
+	public class ContentPageGallery : ContentPage
+	{
+		public ContentPageGallery()
+		{
+			var descriptionLabel =
+				new Label { Text = "ContentPage Galleries", Margin = new Thickness(2, 2, 2, 2) };
+
+			Title = "ContentPage Galleries";
+
+			Content = new ScrollView
+			{
+				Content = new StackLayout
+				{
+					Children =
+					{
+						descriptionLabel,
+						GalleryBuilder.NavButton("ContentPage BackgroundImage", () =>
+							new ContentPageBackgroundImageGallery(), Navigation),
+						GalleryBuilder.NavButton("ContentPage Background", () =>
+							new ContentPageBackgroundGallery(), Navigation),
+					}
+				}
+			};
+		}
+	}
+}

src/Core/src/Platform/iOS/ViewExtensions.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Numerics;
 using System.Threading.Tasks;
+using CoreAnimation;
 using CoreGraphics;
 using Foundation;
 using Microsoft.Maui.Devices;
@@ -264,16 +265,23 @@ public static void UpdateBackgroundLayerFrame(this UIView view)
 
 			var layer = view.Layer;
 
+			UpdateBackgroundLayerFrame(layer, view.Bounds);
+		}
+
+		static void UpdateBackgroundLayerFrame(CALayer layer, CGRect bounds)
+		{
 			if (layer == null || layer.Sublayers == null || layer.Sublayers.Length == 0)
 				return;
-
+						
 			foreach (var sublayer in layer.Sublayers)
 			{
-				if (sublayer.Name == BackgroundLayerName && sublayer.Frame != view.Bounds)
+				if (sublayer.Name == BackgroundLayerName && sublayer.Frame != bounds)
 				{
-					sublayer.Frame = view.Bounds;
+					sublayer.Frame = bounds;
 					break;
 				}
+
+				UpdateBackgroundLayerFrame(sublayer, bounds);
 			}
 		}
 

src/Core/tests/DeviceTests/Handlers/ContentView/ContentViewTests.iOS.cs

@@ -1,22 +1,31 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Reflection.Metadata;
 using System.Threading.Tasks;
-using Microsoft.Maui.Controls;
 using Microsoft.Maui.DeviceTests.Stubs;
-using Microsoft.Maui.Graphics;
-using Microsoft.Maui.Handlers;
-using ObjCRuntime;
 using UIKit;
-using UserNotificationsUI;
 using Xunit;
 
 namespace Microsoft.Maui.DeviceTests.Handlers.ContentView
 {
 	[Category(TestCategory.ContentView)]
 	public partial class ContentViewTests
 	{
+		[Theory(DisplayName = "Background Updates Correctly")]
+		[InlineData(0xFF0000)]
+		[InlineData(0x00FF00)]
+		[InlineData(0x0000FF)]
+		public async Task BackgroundUpdatesCorrectly(uint color)
+		{
+			var expected = Color.FromUint(color);
+
+			var contentView = new ContentViewStub()
+			{
+				Content = new LabelStub { Text = "Background", TextColor = Colors.White },
+				Background = new LinearGradientPaintStub(Colors.Red, Colors.Blue),
+			};
+
+			await ValidateHasColor(contentView, expected);
+		}
+
 		[Fact, Category(TestCategory.FlowDirection)]
 		public async Task FlowDirectionPropagatesToContent()
 		{
@@ -114,5 +123,18 @@ public async Task DoesNotPropagateToContentWithExplicitFlowDirection()
 
 			Assert.Equal(UIUserInterfaceLayoutDirection.LeftToRight, labelFlowDirection);
 		}
+
+		Platform.ContentView GetNativeContentView(ContentViewHandler contentViewHandler) =>
+			contentViewHandler.PlatformView;
+
+		Task ValidateHasColor(IContentView contentView, Color color, Action action = null)
+		{
+			return InvokeOnMainThreadAsync(() =>
+			{
+				var nativeContentView = GetNativeContentView(CreateHandler(contentView));
+				action?.Invoke();
+				nativeContentView.AssertContainsColor(color);
+			});
+		}
 	}
 }