[iOS] Default BarTextColor/BarBackgroundColor will no longer override values set in custom renderers (#233)

* [Controls] Improve TabbedPage test case

iOS should default to the color used in a custom renderer instead of to
the global default color.

* [iOS] TabbedPage Bar*Color default is better

Will use the color set by a custom renderer, if any, instead of always
pulling from global appearance.

Author: samhouts

Xamarin.Forms.ControlGallery.iOS/CustomRenderers.cs

@@ -28,7 +28,7 @@
 [assembly: ExportRenderer(typeof(NativeListView2), typeof(NativeiOSListViewRenderer))]
 [assembly: ExportRenderer(typeof(NativeListView), typeof(NativeListViewRenderer))]
 [assembly: ExportRenderer(typeof(CustomMapView), typeof(CustomIOSMapRenderer))]
-
+[assembly: ExportRenderer(typeof(TabbedPage), typeof(TabbedPageWithCustomBarColorRenderer))]
 namespace Xamarin.Forms.ControlGallery.iOS
 {
 	public class CustomIOSMapRenderer : ViewRenderer<CustomMapView, MKMapView>
@@ -593,5 +593,16 @@ public CollectionViewCell(RectangleF frame) : base(frame)
 		}
 	}
 
+	public class TabbedPageWithCustomBarColorRenderer : TabbedRenderer
+	{
+		public TabbedPageWithCustomBarColorRenderer()
+		{
+			TabBar.TintColor = UIColor.White;
+			TabBar.BarTintColor = UIColor.Purple;
+
+			//UITabBar.Appearance.TintColor = UIColor.White;
+			//UITabBar.Appearance.BarTintColor = UIColor.Purple;
+		}
+	}
 }
 

Xamarin.Forms.Controls/CoreGallery.cs

@@ -69,6 +69,17 @@ internal class CoreNavigationPage : NavigationPage
 		public CoreNavigationPage ()
 		{
 			AutomationId = "NavigationPageRoot";
+
+			BarBackgroundColor = Color.Maroon;
+			BarTextColor = Color.Yellow;
+
+			Device.StartTimer(TimeSpan.FromSeconds(2), () => {
+				BarBackgroundColor = Color.Default;
+				BarTextColor = Color.Default;
+
+				return false;
+			});
+
 			Navigation.PushAsync (new CoreRootPage (this));
 		}
 	}
@@ -85,8 +96,20 @@ public CoreTabbedPage ()
 		{
 			AutomationId = "TabbedPageRoot";
 
-			BarBackgroundColor = Color.Maroon;
-			BarTextColor = Color.White;
+
+			Device.StartTimer(TimeSpan.FromSeconds(6), () => {
+				BarBackgroundColor = Color.Maroon;
+				BarTextColor = Color.Yellow;
+
+				Device.StartTimer(TimeSpan.FromSeconds(6), () => {
+					BarBackgroundColor = Color.Default;
+					BarTextColor = Color.Default;
+
+					return false;
+				});
+
+				return false;
+			});
 
 			Children.Add(new CoreRootPage(this, NavigationBehavior.PushModalAsync) { Title = "Tab 1" });
 			Children.Add(new CoreRootPage(this, NavigationBehavior.PushModalAsync) { Title = "Tab 2" });

Xamarin.Forms.Platform.iOS/Renderers/TabbedRenderer.cs

@@ -23,6 +23,12 @@ namespace Xamarin.Forms.Platform.iOS
 {
 	public class TabbedRenderer : UITabBarController, IVisualElementRenderer, IEffectControlProvider
 	{
+		bool _barBackgroundColorWasSet;
+		bool _barTextColorWasSet;
+		UIColor _defaultBarTextColor;
+		bool _defaultBarTextColorSet;
+		UIColor _defaultBarColor;
+		bool _defaultBarColorSet;
 		bool _loaded;
 		Size _queuedSize;
 
@@ -305,14 +311,31 @@ void UpdateBarBackgroundColor()
 				return;
 
 			var barBackgroundColor = Tabbed.BarBackgroundColor;
+			var isDefaultColor = barBackgroundColor.IsDefault;
+
+			if (isDefaultColor && !_barBackgroundColorWasSet)
+				return;
+
+			if (!_defaultBarColorSet)
+			{
+				if (Forms.IsiOS7OrNewer)
+					_defaultBarColor = TabBar.BarTintColor;
+				else
+					_defaultBarColor = TabBar.TintColor;
+
+				_defaultBarColorSet = true;
+			}
+
+			if (!isDefaultColor)
+				_barBackgroundColorWasSet = true;
 
 			if (Forms.IsiOS7OrNewer)
 			{
-				TabBar.BarTintColor = barBackgroundColor == Color.Default ? UINavigationBar.Appearance.BarTintColor : barBackgroundColor.ToUIColor();
+				TabBar.BarTintColor = isDefaultColor ? _defaultBarColor : barBackgroundColor.ToUIColor();
 			}
 			else
 			{
-				TabBar.TintColor = barBackgroundColor == Color.Default ? UINavigationBar.Appearance.TintColor : barBackgroundColor.ToUIColor();
+				TabBar.TintColor = isDefaultColor ? _defaultBarColor : barBackgroundColor.ToUIColor();
 			}
 		}
 
@@ -322,13 +345,24 @@ void UpdateBarTextColor()
 				return;
 
 			var barTextColor = Tabbed.BarTextColor;
+			var isDefaultColor = barTextColor.IsDefault;
+
+			if (isDefaultColor && !_barTextColorWasSet)
+				return;
+
+			if (!_defaultBarTextColorSet)
+			{
+				_defaultBarTextColor = TabBar.TintColor; 
+				_defaultBarTextColorSet = true;
+			}
 
-			var globalAttributes = UINavigationBar.Appearance.GetTitleTextAttributes();
+			if (!isDefaultColor)
+				_barTextColorWasSet = true;
 
-			var attributes = new UITextAttributes { Font = globalAttributes.Font };
+			var attributes = new UITextAttributes();
 
-			if (barTextColor == Color.Default)
-				attributes.TextColor = globalAttributes.TextColor;
+			if (isDefaultColor)
+				attributes.TextColor = _defaultBarTextColor;
 			else
 				attributes.TextColor = barTextColor.ToUIColor();
 
@@ -341,7 +375,7 @@ void UpdateBarTextColor()
 			// setting the unselected icon tint is not supported by iOS
 			if (Forms.IsiOS7OrNewer)
 			{
-				TabBar.TintColor = barTextColor == Color.Default ? UINavigationBar.Appearance.TintColor : barTextColor.ToUIColor();
+				TabBar.TintColor = isDefaultColor ? _defaultBarTextColor : barTextColor.ToUIColor();
 			}
 		}