[iOS, Mac] Fix for Picker title is not displayed again when SelectedIndex is set to -1 (#30486)

* Fix for Picker title not restoring after deselection on iOS

* Modified test

* Modified AutomationID

* Modified testcase

* [tests] Add windows and mac snapshots

---------

Co-authored-by: Rui Marinho <me@ruimarinho.net>

Author: HarishwaranVijayakumar

src/Controls/tests/TestCases.Android.Tests/snapshots/android/PickerShouldRegainTitle.png

@@ -0,0 +1,37 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 30463, "Picker title is not displayed again", PlatformAffected.iOS)]
+public class Issue30463 : ContentPage
+{
+	public Issue30463()
+	{
+		VerticalStackLayout stackLayout = new VerticalStackLayout
+		{
+			Padding = 20,
+			Spacing = 10
+		};
+
+		Picker picker = new Picker
+		{
+			AutomationId = "RegainingPickerTitle",
+			Title = "Select an item",
+			ItemsSource = new List<string> { "Item 1", "Item 2", "Item 3" },
+			SelectedIndex = 1
+		};
+
+		Button button = new Button
+		{
+			AutomationId = "ToggleSelectedIndexBtn",
+			Text = "Click to change selected index to -1"
+		};
+		button.Clicked += (sender, e) =>
+		{
+			picker.SelectedIndex = -1;
+		};
+
+		stackLayout.Children.Add(picker);
+		stackLayout.Children.Add(button);
+		Content = stackLayout;
+	}
+}
+

src/Controls/tests/TestCases.HostApp/Issues/Issue30463.cs

@@ -0,0 +1,21 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue30463 : _IssuesUITest
+{
+	public Issue30463(TestDevice device) : base(device) { }
+
+	public override string Issue => "Picker title is not displayed again";
+
+	[Test]
+	[Category(UITestCategories.Picker)]
+	public void PickerShouldRegainTitle()
+	{
+		App.WaitForElement("ToggleSelectedIndexBtn");
+		App.Tap("ToggleSelectedIndexBtn");
+		VerifyScreenshot();
+	}
+}

src/Controls/tests/TestCases.Mac.Tests/snapshots/mac/PickerShouldRegainTitle.png

@@ -38,6 +38,7 @@ internal static void UpdatePicker(this MauiPicker platformPicker, IPicker picker
 			}
 			else
 			{
+				platformPicker.Text = null;
 				platformPicker.UpdatePickerTitle(picker);
 			}