[UWP] Fixed EmptyView crash using RefreshView

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue11794.xaml

@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage   
+    xmlns="http://xamarin.com/schemas/2014/forms" 
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
+    x:Class="Xamarin.Forms.Controls.Issues.Issue11794"
+    Title="Issue 11794">
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
+            <RowDefinition />
+            <RowDefinition />
+        </Grid.RowDefinitions>
+        <Label
+            Padding="12"
+            BackgroundColor="Black"
+            TextColor="White"
+            Text="If the CollectionView renders without exceptions with data and being empty, the test has passed."/>
+        <RefreshView
+            Grid.Row="1">
+            <CollectionView 
+                x:Name="EmptyCollectionView">
+                <CollectionView.ItemsLayout>
+                    <GridItemsLayout
+                        Orientation="Vertical"
+                        Span="3" />
+                </CollectionView.ItemsLayout>
+                <CollectionView.ItemTemplate>
+                    <DataTemplate>
+                        <Frame>
+                            <Label
+                                Text="{Binding .}" />
+                        </Frame>
+                    </DataTemplate>
+                </CollectionView.ItemTemplate>
+                <CollectionView.EmptyView>
+                    <StackLayout>
+                        <Label 
+                            Text="Welcome to crashtown" />
+                    </StackLayout>
+                </CollectionView.EmptyView>
+            </CollectionView>
+        </RefreshView>
+        <RefreshView
+            Grid.Row="2">
+            <CollectionView  
+                x:Name="NonEmptyCollectionView"
+                ItemsSource="{Binding Items}">
+                <CollectionView.ItemsLayout>
+                    <GridItemsLayout
+                        Orientation="Vertical"
+                        Span="3" />
+                </CollectionView.ItemsLayout>
+                <CollectionView.ItemTemplate>
+                    <DataTemplate>
+                        <Frame>
+                            <Label
+                                Text="{Binding .}" />
+                        </Frame>
+                    </DataTemplate>
+                </CollectionView.ItemTemplate>
+                <CollectionView.EmptyView>
+                    <StackLayout>
+                        <Label 
+                            Text="Welcome to crashtown" />
+                    </StackLayout>
+                </CollectionView.EmptyView>
+            </CollectionView>
+        </RefreshView>
+    </Grid>
+</ContentPage>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue11794.xaml.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.ObjectModel;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 11794, "[Bug] RefreshView with CollectionView child cannot contain GridItemsLayout with Span greater than 1 in combination with EmptyView on UWP", 
+		PlatformAffected.UWP)]
+	public partial class Issue11794 : ContentPage
+	{
+		public Issue11794()
+		{
+#if APP
+			InitializeComponent();
+			BindingContext = new Issue11794ViewModel();
+#endif
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class Issue11794ViewModel : BindableObject
+	{
+		ObservableCollection<string> _items;
+
+		public Issue11794ViewModel()
+		{
+			LoadItems();
+		}
+
+		public ObservableCollection<string> Items
+		{
+			get { return _items; }
+			set
+			{
+				_items = value;
+				OnPropertyChanged();
+			}
+		}
+
+		void LoadItems()
+		{
+			Items = new ObservableCollection<string>
+			{
+				"Item 1",
+				"Item 2",
+				"Item 3"
+			};
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -26,6 +26,9 @@
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue10744.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10909.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue11794.xaml.cs">
+      <DependentUpon>Issue11794.xaml</DependentUpon>
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue8613.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9137.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8691.cs" />
@@ -2225,4 +2228,10 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
   </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue11794.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+  </ItemGroup>
 </Project>

Xamarin.Forms.Platform.UAP/CollectionView/FormsGridView.cs

@@ -124,7 +124,7 @@ protected override void OnApplyTemplate()
 
 			_emptyViewContentControl = GetTemplateChild("EmptyViewContentControl") as ContentControl;
 
-			if (_emptyView != null)
+			if (_emptyView != null && _emptyViewContentControl != null)
 			{
 				_emptyViewContentControl.Content = _emptyView;
 			}