Fixed the Header and Footer-Name textbox is cut off in collection view

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

@@ -101,24 +101,21 @@ protected override CGRect DetermineEmptyViewFrame()
 		public override void ViewWillLayoutSubviews()
 		{
 			base.ViewWillLayoutSubviews();
+			// This updates the positions of the header view and footer view as their sizes change dynamically
+			var emptyView = CollectionView.ViewWithTag(EmptyTag);
 
-			// This update is only relevant if you have a footer view because it's used to place the footer view
-			// based on the ContentSize so we just update the positions if the ContentSize has changed
-			if (_footerUIView != null)
+			if (IsHorizontal)
 			{
-				var emptyView = CollectionView.ViewWithTag(EmptyTag);
-
-				if (IsHorizontal)
+				if ((_headerUIView is not null && (_headerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width || _headerUIView.Frame.X < emptyView?.Frame.X)) || (_footerUIView is not null && (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width || _footerUIView.Frame.X != _footerUIView.Frame.Width || _footerUIView.Frame.X < emptyView?.Frame.X)))
 				{
-					if (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width ||
-						_footerUIView.Frame.X < emptyView?.Frame.X)
-						UpdateHeaderFooterPosition();
+					UpdateHeaderFooterPosition();
 				}
-				else
+			}
+			else
+			{
+				if ((_headerUIView is not null && (_headerUIView.Frame.Y != ItemsViewLayout.CollectionViewContentSize.Height || _headerUIView.Frame.Y < (emptyView?.Frame.Y + emptyView?.Frame.Height))) || (_footerUIView is not null && (_footerUIView.Frame.Y != ItemsViewLayout.CollectionViewContentSize.Height || _footerUIView.Frame.Y != _footerUIView.Frame.Height || _footerUIView.Frame.Y < (emptyView?.Frame.Y + emptyView?.Frame.Height))))
 				{
-					if (_footerUIView.Frame.Y != ItemsViewLayout.CollectionViewContentSize.Height ||
-						_footerUIView.Frame.Y < (emptyView?.Frame.Y + emptyView?.Frame.Height))
-						UpdateHeaderFooterPosition();
+					UpdateHeaderFooterPosition();
 				}
 			}
 		}
@@ -209,7 +206,9 @@ void UpdateHeaderFooterPosition()
 					_headerUIView.Frame = new CoreGraphics.CGRect(-headerWidth, 0, headerWidth, CollectionView.Frame.Height);
 				}
 
-				if (_footerUIView != null && (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width || emptyWidth > 0))
+				// The FooterView frame is updated when the CollectionView does not contain any items.
+				// Previously, the FooterView frame was updated only for a CollectionView with an ItemSource.
+				if (_footerUIView != null && (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width || _footerUIView.Frame.X != footerWidth || emptyWidth > 0))
 					_footerUIView.Frame = new CoreGraphics.CGRect(ItemsViewLayout.CollectionViewContentSize.Width + emptyWidth, 0, footerWidth, CollectionView.Frame.Height);
 
 				if (CollectionView.ContentInset.Left != headerWidth || CollectionView.ContentInset.Right != footerWidth)
@@ -262,7 +261,9 @@ void UpdateHeaderFooterPosition()
 					height = ItemsViewLayout.CollectionViewContentSize.Height;
 				}
 
-				if (_footerUIView != null && (_footerUIView.Frame.Y != height || emptyHeight > 0))
+				// The FooterView frame is updated when the CollectionView does not contain any items.
+				// Previously, the FooterView frame was updated only for a CollectionView with an ItemSource.
+				if (_footerUIView != null && (_footerUIView.Frame.Y != height || _footerUIView.Frame.Y != footerHeight || emptyHeight > 0))
 				{
 					_footerUIView.Frame = new CoreGraphics.CGRect(0, height + emptyHeight, CollectionView.Frame.Width, footerHeight);
 				}

src/Controls/tests/TestCases.HostApp/Issues/Issue26186.xaml

@@ -0,0 +1,92 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue26186"
+             xmlns:cv1="clr-namespace:Maui.Controls.Sample"
+             xmlns:local="clr-namespace:Maui.Controls.Sample.Issues"
+             Title="Issue26186">
+    <Grid RowDefinitions="Auto, *">
+        <Button Grid.Row="0"
+                Clicked="Button_Clicked"
+                AutomationId="Button"
+                Text="Update width for CollectionView"/>
+        <cv1:CollectionView1 x:Name="collectionView"
+                             AutomationId="CollectionView"
+                             Grid.Row="1">
+            <cv1:CollectionView1.Header>
+                <Grid RowSpacing="10"
+                      ColumnSpacing="10">
+                    <Grid.RowDefinitions>
+                        <RowDefinition Height="*"/>
+                        <RowDefinition Height="*"/>
+                    </Grid.RowDefinitions>
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="Auto"/>
+                        <ColumnDefinition Width="*"/>
+                    </Grid.ColumnDefinitions>
+                    <Label Grid.Row="0"
+                           Grid.Column="0"
+                           Text="Name:"
+                           VerticalTextAlignment="Center"/>
+                    <Entry Grid.Row="0"
+                           Grid.Column="1"/>
+                    <Label Grid.Row="1"
+                           Grid.Column="0"
+                           Text="Faction:"
+                           VerticalTextAlignment="Center"/>
+                    <Picker Grid.Row="1"
+                            Grid.Column="1">
+                        <Picker.ItemsSource>
+                            <x:Array Type="{x:Type x:String}">
+                                <x:String>Baboon</x:String>
+                                <x:String>Capuchin Monkey</x:String>
+                                <x:String>Blue Monkey</x:String>
+                                <x:String>Squirrel Monkey</x:String>
+                                <x:String>Golden Lion Tamarin</x:String>
+                                <x:String>Howler Monkey</x:String>
+                                <x:String>Japanese Macaque</x:String>
+                            </x:Array>
+                        </Picker.ItemsSource>
+                    </Picker>
+                </Grid>
+            </cv1:CollectionView1.Header>
+            <cv1:CollectionView1.Footer>
+                <Grid RowSpacing="10"
+                      ColumnSpacing="10">
+                    <Grid.RowDefinitions>
+                        <RowDefinition Height="*"/>
+                        <RowDefinition Height="*"/>
+                    </Grid.RowDefinitions>
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="Auto"/>
+                        <ColumnDefinition Width="*"/>
+                    </Grid.ColumnDefinitions>
+                    <Label Grid.Row="0"
+                           Grid.Column="0"
+                           Text="Name:"
+                           VerticalTextAlignment="Center"/>
+                    <Entry Grid.Row="0"
+                           Grid.Column="1"/>
+                    <Label Grid.Row="1"
+                           Grid.Column="0"
+                           Text="Faction:"
+                           VerticalTextAlignment="Center"/>
+                    <Picker Grid.Row="1"
+                            Grid.Column="1">
+                        <Picker.ItemsSource>
+                            <x:Array Type="{x:Type x:String}">
+                                <x:String>Baboon</x:String>
+                                <x:String>Capuchin Monkey</x:String>
+                                <x:String>Blue Monkey</x:String>
+                                <x:String>Squirrel Monkey</x:String>
+                                <x:String>Golden Lion Tamarin</x:String>
+                                <x:String>Howler Monkey</x:String>
+                                <x:String>Japanese Macaque</x:String>
+                            </x:Array>
+                        </Picker.ItemsSource>
+                    </Picker>
+                </Grid>
+            </cv1:CollectionView1.Footer>
+        </cv1:CollectionView1>
+    </Grid>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue26186.xaml.cs

@@ -0,0 +1,15 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 26186, "When dynamically changing the CollectionView's width, the end portion of the CollectionView header's and footer's children is cut off", PlatformAffected.iOS | PlatformAffected.macOS)]
+public partial class Issue26186 : ContentPage
+{
+	public Issue26186()
+	{
+		InitializeComponent();
+	}
+
+	private void Button_Clicked(object sender, EventArgs e)
+	{
+		collectionView.WidthRequest = 300;
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue26186.cs

@@ -0,0 +1,19 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue26186(TestDevice testDevice) : _IssuesUITest(testDevice)
+{
+    public override string Issue => "When dynamically changing the CollectionView's width, the end portion of the CollectionView header's and footer's children is cut off";
+
+    [Test]
+    [Category(UITestCategories.CollectionView)]
+    public void ShouldHeaderFooterUpdateWithoutCroppingOnResizing()
+    {
+        App.WaitForElement("Button");
+        App.Click("Button");
+        VerifyScreenshot();
+    }
+}