[iOS] MasterDetailPage master icon should be changeable from any page on the stack (#608)

* master detail page master icon could be changed from any page on the stack

* change icon names

* added titles

2 files changed, 45 insertions, 31 deletions

diff --git a/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
index e742fcee..e054a2d3 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs
@@ -35,8 +35,6 @@ namespace Xamarin.Forms.Platform.iOS
 				var parentingViewController = (ParentingViewController)ViewControllers.Last();
 				UpdateLeftBarButtonItem(parentingViewController);
 			});
-
-			
 		}
 
 		Page Current { get; set; }
@@ -621,34 +619,7 @@ namespace Xamarin.Forms.Platform.iOS
 			if ((firstPage != pageBeingRemoved && currentChild != firstPage && NavigationPage.GetHasBackButton(currentChild)) || _parentMasterDetailPage == null)
 				return;
 
-			if (!_parentMasterDetailPage.ShouldShowToolbarButton())
-			{
-				containerController.NavigationItem.LeftBarButtonItem = null;
-				return;
-			}
-
-			var shouldUseIcon = _parentMasterDetailPage.Master.Icon != null;
-			if (shouldUseIcon)
-			{
-				try
-				{
-					containerController.NavigationItem.LeftBarButtonItem =
-						new UIBarButtonItem(new UIImage(_parentMasterDetailPage.Master.Icon), UIBarButtonItemStyle.Plain,
-						(o, e) => _parentMasterDetailPage.IsPresented = !_parentMasterDetailPage.IsPresented);
-				}
-				catch (Exception)
-				{
-					// Throws Exception otherwise would catch more specific exception type
-					shouldUseIcon = false;
-				}
-			}
-
-			if (!shouldUseIcon)
-			{
-				containerController.NavigationItem.LeftBarButtonItem = new UIBarButtonItem(_parentMasterDetailPage.Master.Title,
-					UIBarButtonItemStyle.Plain,
-					(o, e) => _parentMasterDetailPage.IsPresented = !_parentMasterDetailPage.IsPresented);
-			}
+			SetMasterLeftBarButton(containerController, _parentMasterDetailPage);
 		}
 
 		void UpdateTint()
@@ -681,6 +652,36 @@ namespace Xamarin.Forms.Platform.iOS
 			}
 		}
 
+		internal static void SetMasterLeftBarButton(UIViewController containerController, MasterDetailPage masterDetailPage)
+		{
+			if (!masterDetailPage.ShouldShowToolbarButton())
+			{
+				containerController.NavigationItem.LeftBarButtonItem = null;
+				return;
+			}
+
+			EventHandler handler = (o, e) => masterDetailPage.IsPresented = !masterDetailPage.IsPresented;
+
+			bool shouldUseIcon = masterDetailPage.Master.Icon != null;
+			if (shouldUseIcon)
+			{
+				try
+				{
+					containerController.NavigationItem.LeftBarButtonItem = new UIBarButtonItem(new UIImage(masterDetailPage.Master.Icon), UIBarButtonItemStyle.Plain, handler);
+				}
+				catch (Exception)
+				{
+					// Throws Exception otherwise would catch more specific exception type
+					shouldUseIcon = false;
+				}
+			}
+
+			if (!shouldUseIcon)
+			{
+				containerController.NavigationItem.LeftBarButtonItem = new UIBarButtonItem(masterDetailPage.Master.Title, UIBarButtonItemStyle.Plain, handler);
+			}
+		}
+
 		class SecondaryToolbar : UIToolbar
 		{
 			readonly List<UIView> _lines = new List<UIView>();
diff --git a/Xamarin.Forms.Platform.iOS/Renderers/PhoneMasterDetailRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/PhoneMasterDetailRenderer.cs
index b26e3148..fbadc772 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/PhoneMasterDetailRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/PhoneMasterDetailRenderer.cs
@@ -218,7 +218,7 @@ namespace Xamarin.Forms.Platform.iOS
 		void HandleMasterPropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
 			if (e.PropertyName == Page.IconProperty.PropertyName || e.PropertyName == Page.TitleProperty.PropertyName)
-				MessagingCenter.Send<IVisualElementRenderer>(this, NavigationRenderer.UpdateToolbarButtons);
+				UpdateLeftBarButton();
 		}
 
 		void HandlePropertyChanged(object sender, PropertyChangedEventArgs e)
@@ -321,6 +321,19 @@ namespace Xamarin.Forms.Platform.iOS
 			SetNeedsStatusBarAppearanceUpdate();
 		}
 
+		void UpdateLeftBarButton()
+		{
+			var masterDetailPage = Element as MasterDetailPage;
+			if (!(masterDetailPage?.Detail is NavigationPage))
+				return;
+
+			var detailRenderer = Platform.GetRenderer(masterDetailPage.Detail) as UINavigationController;
+
+			UIViewController firstPage = detailRenderer?.ViewControllers.FirstOrDefault();
+			if (firstPage != null)
+				NavigationRenderer.SetMasterLeftBarButton(firstPage, masterDetailPage);
+		}
+
 		public override UIViewController ChildViewControllerForStatusBarHidden()
 		{
 			if (((MasterDetailPage)Element).Detail != null)