[iOS] Dispose pickers properly and automate GC checks (#632)

* dispose datepicker

* add dispose to other pickers

* add ui test

* add dispose to picker model

* change class name

2 files changed, 164 insertions, 1 deletions

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue1023.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue1023.cs
new file mode 100644
index 00000000..a09a49a0
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue1023.cs
@@ -0,0 +1,162 @@
+using System;
+using System.Collections.Generic;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System.Threading;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.None, 1023, "Automate GC checks of picker disposals", PlatformAffected.iOS)]
+	public class Bugzilla1023 : TestNavigationPage
+	{
+		protected override void Init()
+		{
+			PushAsync(new LandingPage1023());
+		}
+
+#if UITEST && __IOS__
+		[Test]
+		public void Bugzilla1023Test()
+		{
+			for (var n = 0; n < 10; n++)
+			{
+				RunningApp.WaitForElement(q => q.Marked("Push"));
+				RunningApp.Tap(q => q.Marked("Push"));
+
+				RunningApp.WaitForElement(q => q.Marked("ListView"));
+				RunningApp.Back();
+			}
+
+			// At this point, the counter can be any value, but it's most likely not zero.
+			// Invoking GC once is enough to clean up all garbage data and set counter to zero
+			RunningApp.WaitForElement(q => q.Marked("GC"));
+			RunningApp.Tap(q => q.Marked("GC"));
+
+			RunningApp.WaitForElement(q => q.Marked("Counter: 0"));
+		}
+#endif
+	}
+
+	[Preserve(AllMembers = true)]
+	public class LandingPage1023 : ContentPage
+	{
+		public static int Counter;
+		public Label Label;
+
+		public LandingPage1023()
+		{
+			Label = new Label
+			{
+				Text = "Counter: " + Counter,
+				HorizontalTextAlignment = TextAlignment.Center,
+				VerticalTextAlignment = TextAlignment.Center
+			};
+
+			Content = new StackLayout
+			{
+				Orientation = StackOrientation.Vertical,
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				Spacing = 15,
+				Children =
+				{
+					new Label
+					{
+						Text = "Click Push to show a ListView. When you hit the Back button, Counter will show the number of pages that have not been finalized yet."
+						+ " If you click GC, the counter should be 0."
+					},
+					Label,
+					new Button
+					{
+						Text = "GC",
+						AutomationId = "GC",
+						Command = new Command(o =>
+						{
+							GC.Collect();
+							GC.WaitForPendingFinalizers();
+							GC.Collect();
+							Label.Text = "Counter: " + Counter;
+						})
+					},
+					new Button
+					{
+						Text = "Push",
+						AutomationId = "Push",
+						Command = new Command(async o =>
+						{
+							await Navigation.PushAsync(new ContentPage1023());
+						})
+					}
+				}
+			};
+		}
+
+		protected override void OnAppearing()
+		{
+			base.OnAppearing();
+
+			if (Label != null)
+				Label.Text = "Counter: " + Counter;
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class ContentPage1023 : ContentPage
+	{
+		public ContentPage1023()
+		{
+			Interlocked.Increment(ref LandingPage1023.Counter);
+			System.Diagnostics.Debug.WriteLine("Page: " + LandingPage1023.Counter);
+
+			Content = new ListView
+			{
+				HasUnevenRows = true,
+				ItemsSource = new List<string> { "DatePicker", "Picker", "TimePicker" },
+				ItemTemplate = new DataTemplateSelector1023(),
+				AutomationId = "ListView"
+			};
+		}
+
+		~ContentPage1023()
+		{
+			Interlocked.Decrement(ref LandingPage1023.Counter);
+			System.Diagnostics.Debug.WriteLine("Page: " + LandingPage1023.Counter);
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class DataTemplateSelector1023 : DataTemplateSelector
+	{
+		public DataTemplate DatePickerTemplate { get; set; }
+		public DataTemplate PickerTemplate { get; set; }
+		public DataTemplate TimePickerTemplate { get; set; }
+
+		public DataTemplateSelector1023()
+		{
+			DatePickerTemplate = new DataTemplate(() => new ViewCell { View = new DatePicker() });
+			PickerTemplate = new DataTemplate(() => new ViewCell { View = new Picker() });
+			TimePickerTemplate = new DataTemplate(() => new ViewCell { View = new TimePicker() });
+		}
+
+		protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
+		{
+			switch (item as string)
+			{
+				case "DatePicker":
+					return DatePickerTemplate;
+				case "Picker":
+					return PickerTemplate;
+				case "TimePicker":
+					return TimePickerTemplate;
+			}
+
+			return null;
+		}
+	}
+}
\ 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 c69e1a31..754133de 100644
--- 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
@@ -177,6 +177,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)InputTransparentIssue.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)IsInvokeRequiredRaceCondition.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)IsPasswordToggleTest.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue1023.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1024.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1025.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1026.cs" />
@@ -634,4 +635,4 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>