[iOS] Fix ContentPage BackgroundImageSource not working

src/Controls/samples/Controls.Sample.UITests/Issues/Issues17789.xaml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue17789"
+             BackgroundImageSource="oasis.jpg">
+    <StackLayout>
+        <Label 
+            AutomationId="WaitForStubControl"
+            Text="Issue 17789"
+            VerticalOptions="Center" 
+            HorizontalOptions="Center" />
+    </StackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample.UITests/Issues/Issues17789.xaml.cs

@@ -0,0 +1,15 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 17789, "ContentPage BackgroundImageSource not working", PlatformAffected.iOS)]
+	public partial class Issue17789 : ContentPage
+	{
+		public Issue17789()
+		{
+			InitializeComponent();
+		}	
+	}
+}

src/Controls/tests/UITests/Tests/Issues/Issue17789.cs

@@ -0,0 +1,22 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.AppiumTests.Issues
+{
+	public class Issue17789 : _IssuesUITest
+	{
+		public Issue17789(TestDevice device) : base(device)
+		{
+		}
+
+		public override string Issue => "ContentPage BackgroundImageSource not working";
+
+		[Test]
+		public void ContentPageBackgroundImageSourceWorks()
+		{
+			App.WaitForElement("WaitForStubControl");
+			VerifyScreenshot();
+		}
+	}
+}

src/Core/src/Handlers/Page/PageHandler.iOS.cs

@@ -23,20 +23,18 @@ protected override ContentView CreatePlatformView()
 
 		public static void MapBackground(IPageHandler handler, IContentView page)
 		{
-			if (handler is IPlatformViewHandler invh && invh.ViewController is not null)
+			if (handler is IPlatformViewHandler platformViewHandler && platformViewHandler.ViewController is not null)
 			{
-				invh.ViewController.View?.UpdateBackground(page);
+				var provider = handler.GetRequiredService<IImageSourceServiceProvider>();
+				platformViewHandler.ViewController.View?.UpdateBackground(page, provider);
 			}
 		}
 
 		public static void MapTitle(IPageHandler handler, IContentView page)
 		{
-			if (handler is IPlatformViewHandler invh && invh.ViewController is not null)
+			if (handler is IPlatformViewHandler platformViewHandler && platformViewHandler.ViewController is not null)
 			{
-				if (page is ITitledElement titled)
-				{
-					invh.ViewController.Title = titled.Title;
-				}
+				platformViewHandler.ViewController.UpdateTitle(page);
 			}
 		}
 	}

src/Core/src/Platform/iOS/PageExtensions.cs

@@ -0,0 +1,23 @@
+using UIKit;
+
+namespace Microsoft.Maui.Platform
+{
+	internal static class PageExtensions
+	{
+		public static void UpdateTitle(this UIViewController viewController, IContentView page)
+		{
+			if (page is not ITitledElement titled)
+				return;
+
+			viewController.Title = titled.Title;
+		}
+
+		public static void UpdateBackground(this UIView platformView, IContentView page, IImageSourceServiceProvider? provider)
+		{
+			if (page.Background is ImageSourcePaint image)
+				platformView.UpdateBackgroundImageSourceAsync(image.ImageSource, provider).FireAndForget();
+			else
+				platformView.UpdateBackground(page);
+		}
+	}
+}