[iOS] Fix issue changing the ItemTemplate on CollectionView dynamically (#7743)

* Fixed Issue 7742: Change CollectionView ItemTemplate programmatically

* Fixed typo

* Removed invalid test

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7742.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7742.cs
new file mode 100644 (file)
index 0000000..ffe4088
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7742.cs
@@ -0,0 +1,112 @@
+using System;
+using System.Collections.Generic;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using NUnit.Framework;
+using Xamarin.Forms.Core.UITests;
+using System.Linq;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if UITEST
+       [Category(UITestCategories.CollectionView)]
+#endif
+       [Preserve(AllMembers = true)]
+       [Issue(IssueTracker.Github, 7742, "(iOS) Changing ItemTemplate does not work as expected", PlatformAffected.iOS)]
+       public class Issue7742 : TestContentPage
+       {
+               CollectionView _collectionView;
+
+               public Issue7742()
+               {
+                       Title = "Issue 7742";
+               }
+
+               protected override void Init()
+               {
+                       var instructions = new Label
+                       {
+                               Text = "Click the Button. If all cells render correctly, then the test passes."
+                       };
+
+                       var button = new Button
+                       {
+                               Text = "Change ItemTemplate",
+                               AutomationId = "TemplateBtn"
+                       };
+
+                       button.Clicked += OnButton1Clicked;
+   
+                       _collectionView = new CollectionView
+                       {
+                               BackgroundColor = Color.LightGreen,
+                               SelectionMode = SelectionMode.None,
+                               HeightRequest = 500
+                       };
+
+                       var lines = new List<Issue7742Model>();
+
+                       for (int i = 0; i < 30; i++)
+                       {
+                               lines.Add(new Issue7742Model() { Text = $"Item {i}" });
+                       }
+
+                       _collectionView.ItemsSource = lines;
+
+                       var stack = new StackLayout();
+
+                       stack.Children.Add(instructions);
+                       stack.Children.Add(button);
+                       stack.Children.Add(_collectionView);
+
+                       Content = stack;
+               }
+
+               void OnButton1Clicked(object sender, EventArgs e)
+               {
+                       _collectionView.ItemTemplate = CreateDataGridTemplate(2);
+               }
+  
+               DataTemplate CreateDataGridTemplate(int columns)
+               {
+                       var template = new DataTemplate(() =>
+                       {
+                               var grid = new Grid() { Padding = new Thickness(0), Margin = 0, RowSpacing = 0, ColumnSpacing = 0 };
+
+                               grid.RowDefinitions.Clear();
+                               grid.ColumnDefinitions.Clear();
+                               grid.Children.Clear();
+                               grid.RowDefinitions.Add(new RowDefinition() { Height = 40 });
+                               grid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });
+                               Label cell;
+                               cell = new Label() { };
+                               cell.SetBinding(Label.TextProperty, "Text");
+                               cell.FontSize = 20;
+                               cell.FontAttributes = FontAttributes.Bold;
+                               cell.BackgroundColor = Color.LightBlue;
+                               grid.Children.Add(cell, 0, 0);
+
+                               for (int i = 0; i < columns; i++)
+                               {
+                                       grid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });
+                                       cell = new Label() { };
+                                       cell.Text = "Col:" + i;
+                                       cell.FontAttributes = FontAttributes.Bold;
+                                       cell.BackgroundColor = Color.Beige;
+                                       grid.Children.Add(cell, i + 1, 0);
+                               }
+                               return grid;
+                       });
+                       return template;
+               }
+       }
+
+       [Preserve(AllMembers = true)]
+       public class Issue7742Model
+       {
+               public string Text { get; set; }
+       }
+}
\ No newline at end of file

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index e11cdf5..078b0fe 100644 (file)
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -1084,6 +1084,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue7395.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7582.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7563.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7742.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7678.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue6491.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue6127.cs" />

diff --git a/Xamarin.Forms.Platform.iOS/CollectionView/ItemsViewRenderer.cs b/Xamarin.Forms.Platform.iOS/CollectionView/ItemsViewRenderer.cs
index 837b1d4..e77d235 100644 (file)
--- a/Xamarin.Forms.Platform.iOS/CollectionView/ItemsViewRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/CollectionView/ItemsViewRenderer.cs
@@ -41,6 +41,10 @@ namespace Xamarin.Forms.Platform.iOS
                        {
                                ItemsViewController.UpdateItemsSource();
                        }
+                       else if (changedProperty.Is(ItemsView.ItemTemplateProperty))
+                       {
+                               UpdateLayout();
+                       }
                        else if (changedProperty.IsOneOf(ItemsView.EmptyViewProperty, ItemsView.EmptyViewTemplateProperty))
                        {
                                ItemsViewController.UpdateEmptyView();