Fix iOS resizing when content in item template changes size

Sample/VirtualListViewSample/Section.cs

@@ -1,6 +1,24 @@
-namespace VirtualListViewSample;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
 
-public class Section : List<string>
+namespace VirtualListViewSample;
+
+public class Section : List<SectionItem>
 {
 	public string Title { get; set; }
 }
+
+public partial class SectionItem : ObservableObject
+{
+	[ObservableProperty]
+	string text;
+
+	[ObservableProperty]
+	bool isDetailVisible;
+
+	[RelayCommand]
+	void ToggleDetail()
+	{
+		IsDetailVisible = !IsDetailVisible;
+	}
+}

Sample/VirtualListViewSample/SectionedAdapter.cs

@@ -2,7 +2,7 @@
 
 namespace VirtualListViewSample;
 
-public class SectionedAdapter : VirtualListViewAdapterBase<Section, string>
+public class SectionedAdapter : VirtualListViewAdapterBase<Section, SectionItem>
 {
 	public SectionedAdapter(IList<Section> items) : base()
 	{
@@ -20,7 +20,7 @@ public override int GetNumberOfSections()
 	public override int GetNumberOfItemsInSection(int sectionIndex)
 		=> Items[sectionIndex].Count;
 
-	public override string GetItem(int sectionIndex, int itemIndex)
+	public override SectionItem GetItem(int sectionIndex, int itemIndex)
 		=> Items[sectionIndex][itemIndex];
 
 	public void AddItem(string sectionTitle, string itemName)
@@ -33,7 +33,7 @@ public void AddItem(string sectionTitle, string itemName)
 			Items.Add(section);
 		}
 
-		section.Add(itemName);
+		section.Add(new SectionItem { Text = itemName });
 		InvalidateData();
 	}
 

Sample/VirtualListViewSample/SectionedAdapterPage.xaml

@@ -30,13 +30,21 @@
 			</vlv:VirtualListView.SectionHeaderTemplate>
 			<vlv:VirtualListView.ItemTemplate>
 				<DataTemplate>
-					<Border
+                    <Grid>
+                        <Border
 					Margin="10,0,0,0"
 					Padding="4"
 					Background="LightBlue"
 					StrokeShape="{RoundRectangle CornerRadius=10}">
-						<Label Margin="10,6,10,6" Text="{Binding .}" />
+                        <VerticalStackLayout>
+                            <Label Margin="10,6,10,6" Text="{Binding Text}" />
+                            <Button Text="Expand" Command="{Binding ToggleDetailCommand}" />
+                            <Border Background="Green" WidthRequest="100" HeightRequest="100" IsVisible="{Binding IsDetailVisible}">
+
+                            </Border>
+                        </VerticalStackLayout>
 					</Border>
+                    </Grid>
 				</DataTemplate>
 			</vlv:VirtualListView.ItemTemplate>
 		</vlv:VirtualListView>

VirtualListView/Apple/CvCell.ios.maccatalyst.cs

@@ -1,8 +1,6 @@
 using CoreGraphics;
 using Foundation;
 using Microsoft.Maui.Platform;
-using Microsoft.VisualBasic;
-using System.Diagnostics.CodeAnalysis;
 using UIKit;
 
 namespace Microsoft.Maui;
@@ -39,15 +37,15 @@ public override UIKeyCommand[] KeyCommands
 		get
 		{
 			if (keyCommands?.TryGetTarget(out var commands) ?? false)
-                return commands;
+				return commands;
 
 			var v = new[]
 			{
 				UIKeyCommand.Create(new NSString("\r"), 0, new ObjCRuntime.Selector("keyCommandSelect")),
 				UIKeyCommand.Create(new NSString(" "), 0, new ObjCRuntime.Selector("keyCommandSelect")),
 			};
 
-            keyCommands = new WeakReference<UIKeyCommand[]>(v);
+			keyCommands = new WeakReference<UIKeyCommand[]>(v);
 
 			return v;
 		}
@@ -121,33 +119,43 @@ public override void PrepareForReuse()
 
 	public void SetupView(IView view)
 	{
-        // Create a new platform native view if we don't have one yet
-        if (!(NativeView?.TryGetTarget(out var _) ?? false))
-        {
+		if (view is VisualElement ve) {
+			ve.MeasureInvalidated += (s, e) => {
+				System.Diagnostics.Debug.WriteLine("Measure invalidated");
+				//this.SizeToFit();
+			};
+		}
+		// if (view is VisualElement ve) {
+		// 	ve.SizeChanged += (s, e) => {
+		// 		this.SetNeedsLayout();
+		// 	};
+		// }
+
+		// Create a new platform native view if we don't have one yet
+		if (!(NativeView?.TryGetTarget(out var _) ?? false))
+		{
 			var nativeView = view.ToPlatform(this.Handler.MauiContext);
-            nativeView.Frame = this.ContentView.Frame;
-            nativeView.AutoresizingMask = UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleWidth;
-
+			nativeView.Frame = this.ContentView.Frame;
+			nativeView.AutoresizingMask = UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleWidth;
 			this.ContentView.AddSubview(nativeView);
-
 			NativeView = new WeakReference<UIView>(nativeView);
-        }
+		}
 
-        if (!(VirtualView?.TryGetTarget(out var virtualView) ?? false) || (virtualView?.Handler is null))
-        {
-            VirtualView = new WeakReference<IView>(view);
-        }
-    }
+		if (!(VirtualView?.TryGetTarget(out var virtualView) ?? false) || (virtualView?.Handler is null))
+		{
+			VirtualView = new WeakReference<IView>(view);
+		}
+	}
 
 	public void UpdatePosition(PositionInfo positionInfo)
 	{
-        PositionInfo = positionInfo;
-        if (VirtualView?.TryGetTarget(out var virtualView) ?? false)
+		PositionInfo = positionInfo;
+		if (VirtualView?.TryGetTarget(out var virtualView) ?? false)
 		{
-            if (virtualView is IPositionInfo viewPositionInfo)
-                viewPositionInfo.Update(positionInfo);
-        }
-    }
+			if (virtualView is IPositionInfo viewPositionInfo)
+				viewPositionInfo.Update(positionInfo);
+		}
+	}
 
 	class TapHandlerCallback
 	{