Address PR feedback

Author: filipnavara

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

@@ -520,16 +520,13 @@ protected virtual void UpdateTemplatedCell(TemplatedCell cell, NSIndexPath index
 
 		void ClearMeasurementCells()
 		{
-			if (_measurementCells is not null)
+			foreach (var measurementCell in _measurementCells.Values)
 			{
-				foreach (var measurementCell in _measurementCells.Values)
-				{
-					measurementCell.LayoutAttributesChanged -= CellLayoutAttributesChanged;
-					measurementCell.Unbind();
-				}
-
-				_measurementCells.Clear();
+				measurementCell.LayoutAttributesChanged -= CellLayoutAttributesChanged;
+				measurementCell.Unbind();
 			}
+
+			_measurementCells.Clear();
 		}
 
 		public virtual NSIndexPath GetIndexForItem(object item)

src/Controls/src/Core/Handlers/Items2/iOS/ItemsViewController2.cs

@@ -218,7 +218,7 @@ void InvalidateLayoutIfItemsMeasureChanged()
 			{
 				if (visibleCells[n] is TemplatedCell2 { MeasureInvalidated: true } cell)
 				{
-					var indexPath = CollectionView.IndexPathForCell(cell);
+					var indexPath = collectionView.IndexPathForCell(cell);
 					if (indexPath is not null && Items.IndexPathHelpers.IsIndexPathValid(ItemsSource, indexPath))
 					{
 						invalidatedIndexPaths ??= [];

src/Controls/tests/DeviceTests/Elements/CollectionView/CollectionViewTests.iOS.cs

@@ -309,8 +309,13 @@ await CreateHandlerAndAddToWindow<THandler>(collectionView, async handler =>
 				// Reset the data source to force another animation and a layout pass
 				collectionView.ItemsSource = null;
 
-				await Task.Delay(100);
-				((UIView)handler.PlatformView).LayoutIfNeeded();
+				var platformView = (UIView)handler.PlatformView;
+				var uiCollectionView = platformView as UICollectionView ?? platformView.Subviews.OfType<UICollectionView>().FirstOrDefault();
+				Assert.NotNull(uiCollectionView);
+				// Force synchronous flush of the ItemsSource reloading
+				await uiCollectionView.PerformBatchUpdatesAsync(() => { });
+				// Force a layout
+				platformView.LayoutIfNeeded();
 			});
 		}