[iOS] Use separate UIWindow for UIAlertController (#481)

* [iOS] Use separate UIWindow for UIAlertController

* Add similar behavior for DisplayActionSheet; consolidate behavior into PresentAlert method

2 files changed, 79 insertions, 0 deletions

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla45743.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla45743.cs
new file mode 100644
index 00000000..46b9c22d
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla45743.cs
@@ -0,0 +1,78 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 45743, "[iOS] Calling DisplayAlert via BeginInvokeOnMainThread blocking other calls on iOS", PlatformAffected.iOS)]
+	public class Bugzilla45743 : TestNavigationPage
+	{
+		protected override void Init()
+		{
+			PushAsync(new ContentPage
+			{
+				Content = new StackLayout
+				{
+					AutomationId = "Page1",
+					Children =
+					{
+						new Label { Text = "Page 1" }
+					}
+				}
+			});
+
+			Device.BeginInvokeOnMainThread(async () =>
+			{
+				await DisplayAlert("Title", "Message", "Accept", "Cancel");
+			});
+
+			Device.BeginInvokeOnMainThread(async () =>
+			{
+				await PushAsync(new ContentPage
+				{
+					AutomationId = "Page2",
+					Content = new StackLayout
+					{
+						Children =
+						{
+							new Label { Text = "Page 2" }
+						}
+					}
+				});
+			});
+
+			Device.BeginInvokeOnMainThread(async () =>
+			{
+				await DisplayAlert("Title 2", "Message", "Accept", "Cancel");
+			});
+
+			Device.BeginInvokeOnMainThread(async () =>
+			{
+				await DisplayActionSheet("ActionSheet Title", "Cancel", "Close", new string[] { "Test", "Test 2" });
+			});
+		}
+
+#if UITEST
+
+#if __IOS__
+		[Test]
+		public void Bugzilla45743Test()
+		{
+			RunningApp.WaitForElement(q => q.Marked("ActionSheet Title"));
+			RunningApp.Tap("Close");
+			RunningApp.WaitForElement(q => q.Marked("Title 2"));
+			RunningApp.Tap("Accept");
+			RunningApp.WaitForElement(q => q.Marked("Title"));
+			RunningApp.Tap("Accept");
+			Assert.True(RunningApp.Query(q => q.Text("Page 2")).Length > 0);
+		}
+#endif
+
+#endif
+	}
+}
\ 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 677ddb9f..263feb5d 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
@@ -133,6 +133,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42832.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla44044.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla44338.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla45743.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CarouselAsync.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34561.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34727.cs" />