Added a UiTest (dotnet#20199)

src/Controls/samples/Controls.Sample.UITests/Issues/Issue20199.xaml

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+<?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"
+             xmlns:ns="clr-namespace:Maui.Controls.Sample.Issues"
+             x:Class="Maui.Controls.Sample.Issues.Issue20199">
+    <TabBar>
+        <ShellContent
+            Title="Home page"
+            ContentTemplate="{DataTemplate ns:Issue20199Page}"
+            Route="MainPage">
+        </ShellContent>
+    </TabBar>
+</Shell>

src/Controls/samples/Controls.Sample.UITests/Issues/Issue20199.xaml.cs

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+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 20199, "[iOS] Page titles do not appear until navigating when pushing a modal page at startup", PlatformAffected.iOS)]
+	public partial class Issue20199 : Shell
+	{
+		public Issue20199()
+		{
+			InitializeComponent();
+		}
+
+		protected override async void OnAppearing()
+		{
+			base.OnAppearing();
+
+			var closeModalPageButton = new Button() { Text = "Hide", AutomationId = "button" };
+			closeModalPageButton.Clicked += (s, e) =>  Navigation.PopAsync();
+
+			var modalPage = new ContentPage() { Content = closeModalPageButton };
+
+			await Navigation.PushModalAsync(modalPage);
+		}
+	}
+
+	public class Issue20199Page : ContentPage { }
+}

src/Controls/tests/UITests/Tests/Issues/Issue20199.cs

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+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.AppiumTests.Issues
+{
+	public class Issue20199 : _IssuesUITest
+	{
+		public override string Issue => "[iOS] Page titles do not appear until navigating when pushing a modal page at startup";
+
+		public Issue20199(TestDevice device) : base(device)
+		{
+		}
+
+		[Test]
+		public void TitleViewShouldBeVisible()
+		{
+			this.IgnoreIfPlatforms(new TestDevice[] { TestDevice.Android, TestDevice.Mac, TestDevice.Windows });
+
+			_ = App.WaitForElement("button");
+			App.Click("button");
+
+			// The test passes if the 'Home Page' title is visible
+			VerifyScreenshot();
+		}
+	}
+}