Fix for CollectionView SelectedItem loses Background after opening an…

…d closing a Modal page (dotnet#26694)

* Fixed-22467 : CollectionView SelectedItem loses Background after opening and closing a Modal page

* UI test images updated

* UI test images updated

* ios UI test image updated

---------

Co-authored-by: praveenkumarkarunanithi <[email protected]>
Co-authored-by: praveenkumarkarunanithi <[email protected]>

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

@@ -140,14 +140,17 @@ internal void UpdateSelectionMode()
 				case SelectionMode.None:
 					CollectionView.AllowsSelection = false;
 					CollectionView.AllowsMultipleSelection = false;
+					ClearsSelectionOnViewWillAppear = true;
 					break;
 				case SelectionMode.Single:
 					CollectionView.AllowsSelection = true;
 					CollectionView.AllowsMultipleSelection = false;
+					ClearsSelectionOnViewWillAppear = false;
 					break;
 				case SelectionMode.Multiple:
 					CollectionView.AllowsSelection = true;
 					CollectionView.AllowsMultipleSelection = true;
+					ClearsSelectionOnViewWillAppear = false;
 					break;
 			}
 

src/Controls/src/Core/Handlers/Items2/iOS/SelectableItemsViewController2.cs

@@ -137,14 +137,17 @@ internal void UpdateSelectionMode()
 				case SelectionMode.None:
 					CollectionView.AllowsSelection = false;
 					CollectionView.AllowsMultipleSelection = false;
+					ClearsSelectionOnViewWillAppear = true;
 					break;
 				case SelectionMode.Single:
 					CollectionView.AllowsSelection = true;
 					CollectionView.AllowsMultipleSelection = false;
+					ClearsSelectionOnViewWillAppear = false;
 					break;
 				case SelectionMode.Multiple:
 					CollectionView.AllowsSelection = true;
 					CollectionView.AllowsMultipleSelection = true;
+					ClearsSelectionOnViewWillAppear = false;
 					break;
 			}
 

src/Controls/tests/TestCases.HostApp/Issues/Issue22467.xaml

@@ -0,0 +1,58 @@
+<?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.Issue22467"
+  xmlns:local="clr-namespace:Maui.Controls.Sample.Issues">
+  <Grid>
+
+    <Grid.RowDefinitions>
+      <RowDefinition Height="Auto"/>
+      <RowDefinition Height="Auto"/>
+    </Grid.RowDefinitions>
+
+    <CollectionView x:Name="ResultCollectionView"
+                    AutomationId="CollectionView"
+                    Grid.Row="0"
+                    MinimumHeightRequest="150"
+                    MaximumHeightRequest="300"
+                    SelectionMode="Single">
+
+      <CollectionView.ItemTemplate>
+        <DataTemplate>
+          <VerticalStackLayout>
+
+            <VisualStateManager.VisualStateGroups>
+              <VisualStateGroup Name="CommonStates">
+                <VisualState Name="Normal"/>
+                <VisualState Name="Selected">
+                  <VisualState.Setters>
+                    <Setter Property="BackgroundColor"
+                            Value="LightGreen"/>
+                  </VisualState.Setters>
+                </VisualState>
+              </VisualStateGroup>
+            </VisualStateManager.VisualStateGroups>
+
+            <Label Text="{Binding}"
+                   FontSize="14"
+                   VerticalTextAlignment="Center"
+                   Margin="25,7,7,7"/>
+
+            <BoxView HeightRequest="1"
+                     BackgroundColor="Black"/>
+
+          </VerticalStackLayout>
+        </DataTemplate>
+      </CollectionView.ItemTemplate>
+    </CollectionView>
+
+    <Button Grid.Row="1"
+            x:Name="CounterBtn"
+            AutomationId="PushModalAsyncButton"
+            Text="Push New Page"
+            SemanticProperties.Hint="Counts the number of times you click"
+            Clicked="CounterBtn_Clicked"
+            HorizontalOptions="Fill"/>
+  </Grid>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue22467.xaml.cs

@@ -0,0 +1,45 @@
+namespace Maui.Controls.Sample.Issues
+{
+    [XamlCompilation(XamlCompilationOptions.Compile)]
+    [Issue(IssueTracker.Github, 22467, "CollectionView SelectedItem Background Reset After Modal Navigation", PlatformAffected.iOS)]
+    public partial class Issue22467 : ContentPage
+    {
+        public Issue22467()
+        {
+            InitializeComponent();
+            List<string> list = new() { "1", "2", "3", "4", "5" };
+            ResultCollectionView.ItemsSource = list;
+			ResultCollectionView.SelectedItem = list[3];
+        }
+
+        private async void CounterBtn_Clicked(object sender, EventArgs e)
+        {
+            await Navigation.PushModalAsync(CreateNewPage1());
+        }
+
+        private ContentPage CreateNewPage1()
+        {
+            var newPage = new ContentPage
+            {
+                Title = "NewPage1",
+                Content = new VerticalStackLayout
+                {
+                    Children =
+                    {
+                        new Button
+                        {
+                            Text = "Pop to Main Page",
+                            AutomationId = "PopModalAsyncButton",
+                            Command = new Command(async () =>
+                            {
+                                await Navigation.PopModalAsync(true);
+                            })
+                        }
+                    }
+                }
+            };
+
+            return newPage;
+        }
+    }
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue22467.cs

@@ -0,0 +1,25 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+    internal class Issue22467 : _IssuesUITest
+    {
+        public Issue22467(TestDevice device) : base(device) { }
+
+        public override string Issue => "CollectionView SelectedItem Background Reset After Modal Navigation";
+
+        [Test]
+        [Category(UITestCategories.CollectionView)]
+        public void CollectionViewSelectedItemBackgroundShouldPersistAfterModalNavigation()
+        {
+            App.WaitForElement("CollectionView");
+            App.Tap("PushModalAsyncButton");
+            App.WaitForElement("PopModalAsyncButton");
+            App.Tap("PopModalAsyncButton");
+            App.WaitForElement("CollectionView");
+            VerifyScreenshot();
+        }
+    }
+}