[iOS] Fix crash/closing wrong modal with FormSheet and tap outside

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue12300.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Threading.Tasks;
+using Xamarin.Forms;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms.PlatformConfiguration;
+using Xamarin.Forms.PlatformConfiguration.iOSSpecific;
+using NavigationPage = Xamarin.Forms.NavigationPage;
+using Page = Xamarin.Forms.Page;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+using Xamarin.Forms.Core.UITests;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 12300, "Crash when dismissing modally presented page on iOS", PlatformAffected.iOS)]
+	public class Issue12300 : TestContentPage
+	{
+		protected override void Init()
+		{
+			var button = new Button()
+			{
+				Text = "Show Modal Page",
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.CenterAndExpand,
+			};
+
+			button.Clicked += (s, a) =>
+			{
+				Navigation.PushModalAsync(new OTNavigationPage(new ModalPage()));
+			};
+
+			Content = new StackLayout()
+			{
+				Children =
+				{
+					button
+				}
+			};
+		}
+
+		public class OTNavigationPage : NavigationPage
+		{
+			public OTNavigationPage(Page page) : base(page)
+			{
+				On<iOS>().SetModalPresentationStyle(UIModalPresentationStyle.PageSheet);
+			}
+		}
+
+		public class ModalPage : ContentPage
+		{
+			public ModalPage()
+			{
+				var button = new Button()
+				{
+					Text = "Hide Modal Page",
+					HorizontalOptions = LayoutOptions.Center,
+					VerticalOptions = LayoutOptions.CenterAndExpand,
+				};
+
+				button.Clicked += (s, a) =>
+				{
+					Navigation.PopModalAsync();
+				};
+
+				Content = new StackLayout()
+				{
+					Children =
+					{
+						button
+					}
+				};
+			}
+
+			private void ButtonClicked(object sender, EventArgs e)
+			{
+				Navigation.PopModalAsync();
+			}
+		}
+	}
+}

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

@@ -1750,6 +1750,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue13616.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13670.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13684.xaml.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue12300.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue12150.cs" />
   </ItemGroup>
   <ItemGroup>

Xamarin.Forms.Platform.iOS/ModalWrapper.cs

@@ -60,17 +60,6 @@ public async void DidDismiss(UIPresentationController presentationController)
 
 		public override void DismissViewController(bool animated, Action completionHandler)
 		{
-			if (PresentedViewController == null)
-			{
-				// After dismissing a UIDocumentMenuViewController, (for instance, if a WebView with an Upload button
-				// is asking the user for a source (camera roll, etc.)), the view controller accidentally calls dismiss
-				// again on itself before presenting the UIImagePickerController; this leaves the UIImagePickerController
-				// without an anchor to the view hierarchy and it doesn't show up. This appears to be an iOS bug.
-
-				// We can work around it by ignoring the dismiss call when PresentedViewController is null.
-				return;
-			}
-
 			base.DismissViewController(animated, completionHandler);
 		}