Fix dotnet#12429

Author: kubaflo

src/Controls/samples/Controls.Sample.Sandbox/DetailPage.xaml

@@ -0,0 +1,25 @@
+<ContentPage
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    x:Class="Maui.Controls.Sample.DetailPage"
+    Title="Detail"
+    xmlns:local="clr-namespace:Maui.Controls.Sample">
+    <!--<Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="50" />
+            <RowDefinition Height="50" />
+            <RowDefinition Height="50" />
+            <RowDefinition Height="50" />
+        </Grid.RowDefinitions>
+        <Entry Text='Hii'
+                Grid.Row="0"
+                ClearButtonVisibility="WhileEditing" />
+        <DatePicker Date="06/21/2022"
+                    Grid.Row="1" />
+        <CheckBox IsChecked="True"
+                    Grid.Row="2" />
+        <Button Text="Click"
+                Grid.Row="3"
+                Clicked="Button_Clicked" />
+    </Grid>-->
+</ContentPage>

src/Controls/samples/Controls.Sample.Sandbox/DetailPage.xaml.cs

@@ -0,0 +1,18 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Graphics;
+
+namespace Maui.Controls.Sample
+{
+	public partial class DetailPage : ContentPage
+	{
+		public DetailPage()
+		{
+			InitializeComponent();
+		}
+
+		//void Button_Clicked(System.Object sender, System.EventArgs e)
+		//{
+		//	Application.Current.UserAppTheme = AppTheme.Dark;
+		//}
+	}
+}

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

@@ -46,6 +46,16 @@ protected override void Dispose(bool disposing)
 					_footerViewFormsElement.MeasureInvalidated -= OnFormsElementMeasureInvalidated;
 				}
 
+				if (_headerUIView is MauiView hv)
+				{
+					hv.LayoutChanged += HeaderView_LayoutChanged;
+				}
+
+				if (_footerUIView is MauiView fv)
+				{
+					fv.LayoutChanged -= FooterView_LayoutChanged;
+				}
+
 				_headerUIView = null;
 				_headerViewFormsElement = null;
 				_footerUIView = null;
@@ -105,15 +115,26 @@ internal void UpdateFooterView()
 			UpdateSubview(ItemsView?.Footer, ItemsView?.FooterTemplate, FooterTag,
 				ref _footerUIView, ref _footerViewFormsElement);
 			UpdateHeaderFooterPosition();
+
+			if (_footerUIView is MauiView mv)
+			{
+				mv.LayoutChanged += FooterView_LayoutChanged;
+			}
 		}
 
 		internal void UpdateHeaderView()
 		{
 			UpdateSubview(ItemsView?.Header, ItemsView?.HeaderTemplate, HeaderTag,
 				ref _headerUIView, ref _headerViewFormsElement);
 			UpdateHeaderFooterPosition();
+
+			if(_headerUIView is MauiView mv)
+			{
+				mv.LayoutChanged += HeaderView_LayoutChanged;
+			}
 		}
 
+
 		internal void UpdateSubview(object view, DataTemplate viewTemplate, nint viewTag, ref UIView uiView, ref VisualElement formsElement)
 		{
 			uiView?.RemoveFromSuperview();
@@ -239,5 +260,15 @@ internal void UpdateLayoutMeasurements()
 			if (_footerViewFormsElement != null)
 				HandleFormsElementMeasureInvalidated(_footerViewFormsElement);
 		}
+
+		private void HeaderView_LayoutChanged(object sender, EventArgs e)
+		{
+			HandleFormsElementMeasureInvalidated(_headerViewFormsElement);
+		}
+
+		private void FooterView_LayoutChanged(object sender, EventArgs e)
+		{
+			HandleFormsElementMeasureInvalidated(_footerViewFormsElement);
+		}
 	}
 }

src/Core/src/Platform/iOS/MauiView.cs

@@ -134,6 +134,7 @@ public override void LayoutSubviews()
 			}
 
 			CrossPlatformArrange(bounds);
+			OnLayoutChanged();
 		}
 
 		public override void SetNeedsLayout()
@@ -174,5 +175,13 @@ public override void MovedToWindow()
 			base.MovedToWindow();
 			_movedToWindow?.Invoke(this, EventArgs.Empty);
 		}
+
+		[UnconditionalSuppressMessage("Memory", "MEM0001", Justification = IUIViewLifeCycleEvents.UnconditionalSuppressMessage)]
+		internal event EventHandler? LayoutChanged;
+
+		private void OnLayoutChanged()
+		{
+			LayoutChanged?.Invoke(this, EventArgs.Empty);
+		}
 	}
 }