[iOS] Fix: CollectionView does not clear selection when SelectedItem is set to null

src/Controls/src/Core/Handlers/Items/iOS/SelectableItemsViewController.cs

@@ -55,37 +55,49 @@ internal void SelectItem(object selectedItem)
 			if (index.Section > -1 && index.Item > -1)
 			{
 				// Ensure the selected index is updated after the collection view's items generation is completed
-				CollectionView.PerformBatchUpdates(null, _ =>
+				if (!CollectionView.IsLoaded())
 				{
-					// Ensure ItemsSource hasn't been disposed
-					if (ItemsSource is EmptySource)
+					CollectionView.PerformBatchUpdates(null, _ =>
 					{
-						return;
-					}
+						ValidateAndSelectItem(selectedItem, originalSource);
+					});
+				}
+				else
+				{
+					ValidateAndSelectItem(selectedItem, originalSource);
+				}
+			}
+		}
 
-					// Exit if the ItemsSource reference no longer matches the one captured at invocation.
-					if (!ReferenceEquals(ItemsView.ItemsSource, originalSource))
-					{
-						return;
-					}
+		void ValidateAndSelectItem(object selectedItem, object originalSource)
+		{
+			// Ensure ItemsSource hasn't been disposed
+			if (ItemsSource is EmptySource)
+			{
+				return;
+			}
 
-					// Recalculate the index for the selectedItem now that the collection may have changed.(Adding, deleting etc..)
-					var updatedIndex = GetIndexForItem(selectedItem);
-					if (updatedIndex.Section < 0 || updatedIndex.Item < 0)
-					{
-						return;
-					}
+			// Exit if the ItemsSource reference no longer matches the one captured at invocation.
+			if (!ReferenceEquals(ItemsView.ItemsSource, originalSource))
+			{
+				return;
+			}
 
-					// Retrieve the current item at that index and verify it still equals the intended selection.
-					var liveItem = GetItemAtIndex(updatedIndex);
-					if (!Equals(liveItem, selectedItem))
-					{
-						return;
-					}
+			// Recalculate the index for the selectedItem now that the collection may have changed.(Adding, deleting etc..)
+			var updatedIndex = GetIndexForItem(selectedItem);
+			if (updatedIndex.Section < 0 || updatedIndex.Item < 0)
+			{
+				return;
+			}
 
-					CollectionView.SelectItem(index, true, UICollectionViewScrollPosition.None);
-				});
+			// Retrieve the current item at that index and verify it still equals the intended selection.
+			var liveItem = GetItemAtIndex(updatedIndex);
+			if (!Equals(liveItem, selectedItem))
+			{
+				return;
 			}
+
+			CollectionView.SelectItem(updatedIndex, true, UICollectionViewScrollPosition.None);
 		}
 
 		// Called by Forms to clear the native selection

src/Controls/src/Core/Handlers/Items2/iOS/SelectableItemsViewController2.cs

@@ -56,37 +56,49 @@ internal void SelectItem(object selectedItem)
 			if (index.Section > -1 && index.Item > -1)
 			{
 				// Ensure the selected index is updated after the collection view's items generation is completed
-				CollectionView.PerformBatchUpdates(null, _ =>
+				if (!CollectionView.IsLoaded())
 				{
-					// Ensure ItemsSource hasn't been disposed
-					if (ItemsSource is Items.EmptySource)
+					CollectionView.PerformBatchUpdates(null, _ =>
 					{
-						return;
-					}
+						ValidateAndSelectItem(selectedItem, originalSource);
+					});
+				}
+				else
+				{
+					ValidateAndSelectItem(selectedItem, originalSource);
+				}
+			}
+		}
 
-					// Exit if the ItemsSource reference no longer matches the one captured at invocation.
-					if (!ReferenceEquals(ItemsView.ItemsSource, originalSource))
-					{
-						return;
-					}
+		private void ValidateAndSelectItem(object selectedItem, object originalSource)
+		{
+			// Ensure ItemsSource hasn't been disposed
+			if (ItemsSource is Items.EmptySource)
+			{
+				return;
+			}
 
-					// Recalculate the index for the selectedItem now that the collection may have changed.(Adding, deleting etc..)
-					var updatedIndex = GetIndexForItem(selectedItem);
-					if (updatedIndex.Section < 0 || updatedIndex.Item < 0)
-					{
-						return;
-					}
+			// Exit if the ItemsSource reference no longer matches the one captured at invocation.
+			if (!ReferenceEquals(ItemsView.ItemsSource, originalSource))
+			{
+				return;
+			}
 
-					// Retrieve the current item at that index and verify it still equals the intended selection.
-					var liveItem = GetItemAtIndex(updatedIndex);
-					if (!Equals(liveItem, selectedItem))
-					{
-						return;
-					}
+			// Recalculate the index for the selectedItem now that the collection may have changed.(Adding, deleting etc..)
+			var updatedIndex = GetIndexForItem(selectedItem);
+			if (updatedIndex.Section < 0 || updatedIndex.Item < 0)
+			{
+				return;
+			}
 
-					CollectionView.SelectItem(index, true, UICollectionViewScrollPosition.None);
-				});
+			// Retrieve the current item at that index and verify it still equals the intended selection.
+			var liveItem = GetItemAtIndex(updatedIndex);
+			if (!Equals(liveItem, selectedItem))
+			{
+				return;
 			}
+
+			CollectionView.SelectItem(updatedIndex, true, UICollectionViewScrollPosition.None);
 		}
 
 		// Called by Forms to clear the native selection

src/Controls/tests/TestCases.HostApp/Issues/Issue26187.cs

@@ -15,8 +15,6 @@ public class CollectionViewSelectedItemNullPage : ContentPage
 	{
 		public ObservableCollection<string> Items { get; set; }
 
-		public string SelectedItem { get; set; }
-
 		public CollectionViewSelectedItemNullPage()
 		{
 			Items = new ObservableCollection<string>
@@ -27,7 +25,6 @@ public CollectionViewSelectedItemNullPage()
 					"Item 4",
 					"Item 5"
 				};
-			SelectedItem = Items.LastOrDefault();
 			var cv = new CollectionView
 			{
 				SelectionMode = SelectionMode.Single,
@@ -51,20 +48,16 @@ public CollectionViewSelectedItemNullPage()
 			};
 
 			cv.SetBinding(CollectionView.ItemsSourceProperty, new Binding(nameof(Items)));
-			//  cv.SetBinding(CollectionView.SelectedItemProperty, new Binding(nameof(SelectedItem)));
 			Content = cv;
-
 			BindingContext = this;
-			//  cv.SelectedItem = SelectedItem;
-
 			cv.SelectionChanged += CollectionView_SelectionChanged;
 		}
 
-		async void CollectionView_SelectionChanged(object sender, SelectionChangedEventArgs e)
+		void CollectionView_SelectionChanged(object sender, SelectionChangedEventArgs e)
 		{
 			if (e.CurrentSelection.FirstOrDefault() is string issue)
 			{
-				await Navigation.PushAsync(new NewPage(issue));
+				_ = Navigation.PushAsync(new NewPage(issue));
 			}
 
 			// Clear Selection

src/Controls/tests/TestCases.HostApp/Issues/Issue30363.cs

@@ -0,0 +1,60 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 30363, "[iOS] CollectionView does not clear selection when SelectedItem is set to null", PlatformAffected.iOS)]
+public class Issue30363 : ContentPage
+{
+	public Issue30363()
+	{
+		ObservableCollection<string> Items = new ObservableCollection<string>
+		{
+			"Item 1",
+			"Item 2",
+			"Item 3",
+			"Item 4",
+			"Item 5"
+		};
+
+
+		var collectionView = new CollectionView
+		{
+			ItemsSource = Items,
+			SelectionMode = SelectionMode.Single,
+			ItemTemplate = new DataTemplate(() =>
+			{
+				var label = new Label
+				{
+					FontSize = 24,
+					HorizontalOptions = LayoutOptions.FillAndExpand,
+					VerticalOptions = LayoutOptions.Center,
+					AutomationId = "cvItem"
+				};
+				label.SetBinding(Label.TextProperty, ".");
+
+				return new Grid
+				{
+					Children = { label }
+				};
+			})
+		};
+
+		collectionView.SelectionChanged += (sender, e) =>
+			{
+				if (e.CurrentSelection.Count > 0)
+				{
+					var selectedItem = e.CurrentSelection[0] as string;
+					if (selectedItem != null)
+					{
+						// Deselect the item
+						collectionView.SelectedItem = null;
+					}
+				}
+			};
+
+		var grid = new Grid();
+		grid.Children.Add(collectionView);
+
+		Content = grid;
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30363.cs

@@ -0,0 +1,23 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue30363 : _IssuesUITest
+{
+	public override string Issue => "[iOS] CollectionView does not clear selection when SelectedItem is set to null";
+
+	public Issue30363(TestDevice device)
+	: base(device)
+	{ }
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void CollectionViewSelectionShouldClear()
+	{
+		App.WaitForElement("cvItem");
+		App.Tap("cvItem");
+		VerifyScreenshot(retryTimeout: TimeSpan.FromSeconds(2));
+	}
+}