[iOS] Implement `ForceUpdateSize` for `TableView` (#3300) fixes #2842

* Add repro for #2842

* [iOS] Implement ForceUpdateSize for TableView

fixes #2842

* Revert changes to TableViewModelRenderer

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2842.cs

@@ -0,0 +1,73 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.Forms.Core.UITests;
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if UITEST
+	[Category(UITestCategories.ManualReview)]
+	[Category(UITestCategories.TableView)]
+	[Category(UITestCategories.Cells)]
+#endif
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 2842, "ViewCell in TableView not adapting to changed size on iOS", PlatformAffected.iOS)]
+	public class Issue2842 : TestContentPage
+	{
+		protected override void Init()
+		{
+			var grid = new Grid
+			{
+				Padding = 10,
+				ColumnDefinitions = { new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) } },
+				RowDefinitions = { new RowDefinition { Height = new GridLength(1, GridUnitType.Auto) }, new RowDefinition { Height = new GridLength(1, GridUnitType.Auto) } }
+			};
+
+			grid.Children.Add(new Label { Text = "I am initially visible." }, 0, 0);
+
+			Label target = new Label { Text = "Success", AutomationId = "lblSuccess", IsVisible = false, TextColor = Color.Red };
+
+			grid.Children.Add(target, 0, 1);
+
+			var tableView = new TableView { HasUnevenRows = true, Intent = TableIntent.Settings };
+
+			ViewCell viewCell = new ViewCell { View = grid };
+			TableSection item = new TableSection
+			{
+				viewCell,
+				new ImageCell {  ImageSource = "cover1.jpg" }
+			};
+
+			tableView.Root.Add(item);
+
+			var button = new Button
+			{
+				Text = "Click me",
+				AutomationId = "btnClick",
+				Command = new Command(() =>
+				{
+					target.IsVisible = true;
+					viewCell.ForceUpdateSize();
+				})
+			};
+
+			var label = new Label { Text = "Tap the button to expand the cell. If the cell does not expand and the red text is on top of the image, this test has failed." };
+
+			Content = new StackLayout { Children = { label, button, tableView }, Margin = 20 };
+		}
+
+#if UITEST
+		[Test]
+		public void Issue2842Test() 
+		{
+			RunningApp.WaitForElement (q => q.Marked ("btnClick"));
+			RunningApp.Tap (q => q.Marked ("btnClick"));
+			RunningApp.Screenshot ("Verify that the text is not on top of the image");
+		}
+#endif
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -480,6 +480,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue2837.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue2740.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1939.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue2842.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1666.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue2838.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)_Template.cs" />

Xamarin.Forms.Core.UITests.Shared/UITestCategories.cs

@@ -28,6 +28,7 @@
 		public const string Slider = "Slider";
 		public const string Stepper = "Stepper";
 		public const string Switch = "Switch";
+		public const string TableView = "TableView";
 		public const string TimePicker = "TimePicker";
 		public const string ToolbarItem = "ToolbarItem";
 		public const string WebView = "WebView";

Xamarin.Forms.Core/Cells/Cell.cs

@@ -111,7 +111,7 @@ namespace Xamarin.Forms
 			if (_nextCallToForceUpdateSizeQueued)
 				return;
 
-			if ((Parent as ListView)?.HasUnevenRows == true)
+			if ((Parent as ListView)?.HasUnevenRows == true || (Parent as TableView)?.HasUnevenRows == true)
 			{
 				_nextCallToForceUpdateSizeQueued = true;
 				OnForceUpdateSizeRequested();

Xamarin.Forms.Platform.iOS/Renderers/TableViewModelRenderer.cs

@@ -32,6 +32,7 @@ namespace Xamarin.Forms.Platform.iOS
 			var cell = View.Model.GetCell(indexPath.Section, indexPath.Row);
 
 			var nativeCell = CellTableViewCell.GetNativeCell(tableView, cell);
+
 			return nativeCell;
 		}