Invalidate layout on ViewCell if Measurements change (#7755)

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2354.cs

@@ -30,7 +30,7 @@ namespace Xamarin.Forms.Controls.Issues
 
 			var cell = new DataTemplate (typeof(CustomCell));
 
-			var listView = new ListView {
+			var listView = new ListView(ListViewCachingStrategy.RecycleElement) {
 				ItemsSource = presidents,
 				ItemTemplate = cell,
 				RowHeight = 200

Xamarin.Forms.Platform.iOS/Cells/CellRenderer.cs

@@ -1,4 +1,5 @@
 using System;
+using System.ComponentModel;
 using UIKit;
 using Xamarin.Forms.Internals;
 using Xamarin.Forms.PlatformConfiguration.iOSSpecific;
@@ -10,6 +11,7 @@ namespace Xamarin.Forms.Platform.iOS
 		static readonly BindableProperty RealCellProperty = BindableProperty.CreateAttached("RealCell", typeof(UITableViewCell), typeof(Cell), null);
 
 		EventHandler _onForceUpdateSizeRequested;
+		PropertyChangedEventHandler _onPropertyChangedEventHandler;
 
 		public virtual UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)
 		{
@@ -89,8 +91,12 @@ namespace Xamarin.Forms.Platform.iOS
 
 		protected void WireUpForceUpdateSizeRequested(ICellController cell, UITableViewCell nativeCell, UITableView tableView)
 		{
+			var inpc = cell as INotifyPropertyChanged;
 			cell.ForceUpdateSizeRequested -= _onForceUpdateSizeRequested;
 
+			if (inpc != null)
+				inpc.PropertyChanged -= _onPropertyChangedEventHandler;
+
 			_onForceUpdateSizeRequested = (sender, e) =>
 			{
 				var index = tableView?.IndexPathForCell(nativeCell) ?? (sender as Cell)?.GetIndexPath();
@@ -98,7 +104,30 @@ namespace Xamarin.Forms.Platform.iOS
 					tableView.ReloadRows(new[] { index }, UITableViewRowAnimation.None);
 			};
 
+			_onPropertyChangedEventHandler = (sender, e) =>
+			{
+				if(e.PropertyName == "RealCell" && sender is BindableObject bo && GetRealCell(bo) == null)
+				{
+					if(sender is ICellController icc)
+						icc.ForceUpdateSizeRequested -= _onForceUpdateSizeRequested;
+
+					if (sender is INotifyPropertyChanged notifyPropertyChanged)
+						notifyPropertyChanged.PropertyChanged -= _onPropertyChangedEventHandler;
+
+					_onForceUpdateSizeRequested = null;
+					_onPropertyChangedEventHandler = null;
+				}
+			};
+
 			cell.ForceUpdateSizeRequested += _onForceUpdateSizeRequested;
+			if (inpc != null)
+				inpc.PropertyChanged += _onPropertyChangedEventHandler;
+
+		}
+
+		void Ncp_PropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+			System.Diagnostics.Debug.WriteLine($"{e.PropertyName}");
 		}
 
 		internal static UITableViewCell GetRealCell(BindableObject cell)

Xamarin.Forms.Platform.iOS/Cells/CellTableViewCell.cs

@@ -108,6 +108,7 @@ namespace Xamarin.Forms.Platform.iOS
 				if (_cell != null)
 				{
 					_cell.PropertyChanged -= HandlePropertyChanged;
+					CellRenderer.SetRealCell(_cell, null);
 				}
 				_cell = null;
 			}

Xamarin.Forms.Platform.iOS/Cells/ViewCellRenderer.cs

@@ -9,6 +9,10 @@ namespace Xamarin.Forms.Platform.iOS
 {
 	public class ViewCellRenderer : CellRenderer
 	{
+		public ViewCellRenderer()
+		{
+		}
+
 		public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)
 		{
 			Performance.Start(out string reference);
@@ -141,6 +145,8 @@ namespace Xamarin.Forms.Platform.iOS
 					if (_viewCell != null)
 					{
 						_viewCell.PropertyChanged -= ViewCellPropertyChanged;
+						_viewCell.View.MeasureInvalidated -= OnMeasureInvalidated;
+						SetRealCell(_viewCell, null);
 					}
 					_viewCell = null;
 				}
@@ -170,6 +176,7 @@ namespace Xamarin.Forms.Platform.iOS
 				{
 					Device.BeginInvokeOnMainThread(oldCell.SendDisappearing);
 					oldCell.PropertyChanged -= ViewCellPropertyChanged;
+					oldCell.View.MeasureInvalidated -= OnMeasureInvalidated;
 				}
 
 				_viewCell = cell;
@@ -201,9 +208,16 @@ namespace Xamarin.Forms.Platform.iOS
 
 				Platform.SetRenderer(_viewCell.View, renderer);
 				UpdateIsEnabled(_viewCell.IsEnabled);
+				_viewCell.View.MeasureInvalidated += OnMeasureInvalidated;
 				Performance.Stop(reference);
 			}
 
+			void OnMeasureInvalidated(object sender, EventArgs e)
+			{
+				SetNeedsLayout();
+			}
+
+			
 		}
 	}
 }