[iOS] Shell toolbar items (#20510)

* Shell toolbar items fix

* Added snapshots

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellPageRendererTracker.cs

@@ -292,17 +292,25 @@ protected virtual void UpdateToolbarItems()
 					NavigationItem.RightBarButtonItems[i].Dispose();
 			}
 
+			var shellToolbarItems = _context?.Shell?.ToolbarItems;
 			List<UIBarButtonItem> primaries = null;
-			if (Page.ToolbarItems.Count > 0)
+			if (Page.ToolbarItems.Count > 0) // Display toolbar items defined on the current page
 			{
 				foreach (var item in System.Linq.Enumerable.OrderBy(Page.ToolbarItems, x => x.Priority))
 				{
 					(primaries = primaries ?? new List<UIBarButtonItem>()).Add(item.ToUIBarButtonItem(false, true));
 				}
-
-				if (primaries != null)
-					primaries.Reverse();
 			}
+			else if (shellToolbarItems != null && shellToolbarItems.Count > 0) // If the page has no toolbar items use the ones defined for the shell
+			{
+				foreach (var item in System.Linq.Enumerable.OrderBy(shellToolbarItems, x => x.Priority))
+				{
+					(primaries = primaries ?? new List<UIBarButtonItem>()).Add(item.ToUIBarButtonItem(false, true));
+				}
+			}
+
+			if (primaries != null)
+				primaries.Reverse();
 
 			NavigationItem.SetRightBarButtonItems(primaries == null ? Array.Empty<UIBarButtonItem>() : primaries.ToArray(), false);
 

src/Controls/tests/TestCases.HostApp/Issues/Issue18946.xaml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue18946">
+    <Shell.TitleView>
+        <HorizontalStackLayout Margin="10" HorizontalOptions="Center" VerticalOptions="Fill" >
+            <Image AutomationId="image" Source="small_dotnet_bot.png" HeightRequest="48" WidthRequest="48" />
+            <Label VerticalOptions="Center" VerticalTextAlignment="Center" Text="Maui App" FontSize="20" />
+        </HorizontalStackLayout>
+    </Shell.TitleView>
+
+    <Shell.ToolbarItems>
+        <ToolbarItem Text="Hello"/>
+    </Shell.ToolbarItems>
+
+    <ShellContent Title="Home" Route="MainPage">
+        <ContentPage>
+            <Label Text="Hello, MAUI!" AutomationId="label"/>
+        </ContentPage>
+    </ShellContent>
+</Shell>

src/Controls/tests/TestCases.HostApp/Issues/Issue18946.xaml.cs

@@ -0,0 +1,16 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 18946, "Shell Toolbar items not displayed", PlatformAffected.All)]
+	public partial class Issue18946 : Shell
+	{
+		public Issue18946()
+		{
+			InitializeComponent();
+		}
+	}
+
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue18946.cs

@@ -0,0 +1,24 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue18946 : _IssuesUITest
+	{
+		public override string Issue => "Shell Toolbar items not displayed";
+
+		public Issue18946(TestDevice device) : base(device)
+		{ }
+
+		[Test]
+		[Category(UITestCategories.Shell)]
+		public void ToolbarItemsShouldWork()
+		{
+			_ = App.WaitForElement("label");
+
+			// The test passes if the text 'hello' is visible in the toolbar
+			VerifyScreenshot();
+		}
+	}
+}