[iOS] Revert changes in popping navigation (#547)

* [iOS] Revert changes in popping navigation

* [iOS] Remove unified if

1 files changed, 44 insertions, 27 deletions

diff --git a/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
index 18000b7f..adf32192 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
@@ -97,11 +97,25 @@ namespace Xamarin.Forms.Platform.iOS
 			return OnPopToRoot(page, animated);
 		}
 
+		public override UIViewController[] PopToRootViewController(bool animated)
+		{
+			if (!_ignorePopCall && ViewControllers.Length > 1)
+				RemoveViewControllers(animated);
+
+			return base.PopToRootViewController(animated);
+		}
+
 		public Task<bool> PopViewAsync(Page page, bool animated = true)
 		{
 			return OnPopViewAsync(page, animated);
 		}
 
+		public override UIViewController PopViewController(bool animated)
+		{
+			RemoveViewControllers(animated);
+			return base.PopViewController(animated);
+		}
+
 		public Task<bool> PushPageAsync(Page page, bool animated = true)
 		{
 			return OnPushAsync(page, animated);
@@ -501,9 +515,6 @@ namespace Xamarin.Forms.Platform.iOS
 
 			// In the future we may want to make RemovePageAsync and deprecate RemovePage to handle cases where Push/Pop is called
 			// during a remove cycle. 
-			var parentingVC = target as ParentingViewController;
-			if (parentingVC != null)
-				parentingVC.IgnorePageBeingRemoved = true;
 
 			if (_removeControllers == null)
 			{
@@ -520,6 +531,36 @@ namespace Xamarin.Forms.Platform.iOS
 			UpdateLeftBarButtonItem(parentingViewController, page);
 		}
 
+		void RemoveViewControllers(bool animated)
+		{
+			var controller = TopViewController as ParentingViewController;
+			if (controller == null || controller.Child == null)
+				return;
+
+			// Gesture in progress, lets not be proactive and just wait for it to finish
+			var count = ViewControllers.Length;
+			var task = GetAppearedOrDisappearedTask(controller.Child);
+			task.ContinueWith(async t =>
+			{
+				// task returns true if the user lets go of the page and is not popped
+				// however at this point the renderer is already off the visual stack so we just need to update the NavigationPage
+				// Also worth noting this task returns on the main thread
+				if (t.Result)
+					return;
+				_ignorePopCall = true;
+				// because iOS will just chain multiple animations together...
+				var removed = count - ViewControllers.Length;
+				for (var i = 0; i < removed; i++)
+				{
+					// lets just pop these suckers off, do not await, the true is there to make this fast
+					await ((INavigationPageController)Element).PopAsyncInner(animated, true);
+				}
+				// because we skip the normal pop process we need to dispose ourselves
+				controller.Dispose();
+				_ignorePopCall = false;
+			}, TaskScheduler.FromCurrentSynchronizationContext());
+		}
+
 		void UpdateBackgroundColor()
 		{
 			var color = Element.BackgroundColor == Color.Default ? Color.White : Element.BackgroundColor;
@@ -761,12 +802,6 @@ namespace Xamarin.Forms.Platform.iOS
 				}
 			}
 
-			public bool IgnorePageBeingRemoved
-			{
-				get;
-				set;
-			}
-
 			public event EventHandler Appearing;
 
 			public override void DidRotate(UIInterfaceOrientation fromInterfaceOrientation)
@@ -822,24 +857,6 @@ namespace Xamarin.Forms.Platform.iOS
 				base.ViewWillAppear(animated);
 			}
 
-			public override async void DidMoveToParentViewController(UIViewController parent)
-			{
-				//If Parent of our child is already null we removed this using our API
-				//If we still have parent and we are removing our render we need to update our navigation
-				if (parent == null && !IgnorePageBeingRemoved)
-				{
-					NavigationRenderer n;
-					if (_navigation.TryGetTarget(out n))
-					{
-						var navController = n.Element as INavigationPageController;
-						await navController?.PopAsyncInner(true, true);
-					}
-
-				}
-				base.DidMoveToParentViewController(parent);
-
-			}
-
 			protected override void Dispose(bool disposing)
 			{
 				if (disposing)