Pickers Inside CollectionView get SelectedItem Cleared on Scrolling -…

… fix

src/Controls/src/Core/Picker/Picker.cs

@@ -278,9 +278,7 @@ void OnItemsSourceChanged(IList oldValue, IList newValue)
 			}
 			else
 			{
-				// Unlock, then clear, so OnItemsCollectionChanged executes
 				((LockableObservableListWrapper)Items).IsLocked = false;
-				((LockableObservableListWrapper)Items).InternalClear();
 			}
 		}
 

src/Controls/tests/TestCases.HostApp/Issues/Issue25842.xaml

@@ -0,0 +1,59 @@
+<?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.Issue25842">
+    <ContentView>
+        <CollectionView HeightRequest="600"
+            AutomationId="CollectionView"
+                VerticalOptions="Center"
+                ItemsSource="{Binding Students}">
+            <CollectionView.ItemsLayout>
+                <GridItemsLayout
+                    Orientation="Vertical"
+                    Span="1"
+                    HorizontalItemSpacing="10"
+                    VerticalItemSpacing="10"/>
+            </CollectionView.ItemsLayout>
+            <CollectionView.ItemTemplate>
+                <DataTemplate>
+                    <Border Stroke="Black"
+                            StrokeThickness="1"
+                            Padding="10"
+                            BackgroundColor="Gray"
+                            StrokeShape="RoundRectangle 10">
+                        <VerticalStackLayout Spacing="10">
+                            <HorizontalStackLayout VerticalOptions="FillAndExpand"
+                                                   HorizontalOptions="FillAndExpand"
+                                                   Spacing="10">
+                                <Label Text="Name:"
+                                       FontAttributes="Bold"
+                                       VerticalOptions="CenterAndExpand"
+                                       HorizontalOptions="FillAndExpand"/>
+                                <Label Text="{Binding Name}"
+                                       FontSize="Medium"
+                                       VerticalOptions="CenterAndExpand"
+                                       HorizontalOptions="FillAndExpand"/>
+                            </HorizontalStackLayout>
+
+                            <HorizontalStackLayout VerticalOptions="FillAndExpand"
+                                                   HorizontalOptions="FillAndExpand"
+                                                   Spacing="10">
+                                <Label Text="Country:"
+                                       FontAttributes="Bold"
+                                       VerticalOptions="CenterAndExpand"
+                                       HorizontalOptions="FillAndExpand"/>
+                                <Picker Title="Country"
+                                        WidthRequest="300"
+                                        ItemsSource="{Binding Countries}"
+                                        SelectedItem="{Binding Country}"
+                                        VerticalOptions="CenterAndExpand"
+                                        HorizontalOptions="FillAndExpand"
+                                        FontSize="Medium"/>
+                            </HorizontalStackLayout>
+                        </VerticalStackLayout>
+                    </Border>
+                </DataTemplate>
+            </CollectionView.ItemTemplate>
+        </CollectionView>
+    </ContentView>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue25842.xaml.cs

@@ -0,0 +1,42 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 25842, "Pickers Inside CollectionView get SelectedItem Cleared on Scrolling", PlatformAffected.iOS)]
+public partial class Issue25842 : ContentPage
+{
+	public Issue25842()
+	{
+		InitializeComponent();
+		BindingContext = new Issue25842ViewModel();
+	}
+
+	class Issue25842ViewModel
+	{
+		public ObservableCollection<Student> Students { get; set; }
+
+		public Issue25842ViewModel()
+		{
+			Students = new()
+			{
+				new () { Name = "John Doe", Country = "United States" },
+				new () { Name = "Jane Smith", Country = "Canada" },
+				new () { Name = "Sam Brown", Country = "India" },
+				new () { Name = "Lisa White", Country = "United States" },
+				new () { Name = "Tom Green", Country = "Canada" },
+				new () { Name = "Emma Black", Country = "India" },
+				new () { Name = "Noah Blue", Country = "United States" },
+				new () { Name = "Olivia Yellow", Country = "Canada" },
+				new () { Name = "Liam Brown", Country = "India" },
+				new () { Name = "Sophia Pink", Country = "United States" }
+			};
+		}
+
+		public class Student
+		{
+			public required string Name { get; set; }
+			public required string Country { get; set; }
+			public ObservableCollection<string> Countries { get; set; } = new() { "United States", "Canada", "India" };
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25842.cs

@@ -0,0 +1,27 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue25842 : _IssuesUITest
+	{
+		public Issue25842(TestDevice testDevice) : base(testDevice)
+		{
+		}
+
+		public override string Issue => "Pickers Inside CollectionView get SelectedItem Cleared on Scrolling";
+
+		[Test]
+		[Description("Verify that OnTapped is fired every time a ViewCell is tapped")]
+		[Category(UITestCategories.CollectionView)]
+		[Category(UITestCategories.Picker)]
+		public void SelectedPickerItemsShouldNotClear()
+		{
+			App.WaitForElement("CollectionView");
+			App.ScrollDown("CollectionView");
+			App.ScrollUp("CollectionView");
+			VerifyScreenshot();
+		}
+	}
+}