[iOS] Use UIButtonType.System for Button and utilize UIButton.Appearance (#554)

* Change button style and use UIButton appearance

* added sample code

* change references

* setting other properties

* add comment

* refactor proxy setter

* made control states array static

* remove category declaration

* changes

* add sample code

* changes

* Fix identation

* Update ButtonRenderer.cs

6 files changed, 195 insertions, 10 deletions

diff --git a/Xamarin.Forms.ControlGallery.iOS/AppDelegate.cs b/Xamarin.Forms.ControlGallery.iOS/AppDelegate.cs
index d3107735..1aed7738 100644
--- a/Xamarin.Forms.ControlGallery.iOS/AppDelegate.cs
+++ b/Xamarin.Forms.ControlGallery.iOS/AppDelegate.cs
@@ -205,7 +205,7 @@ namespace Xamarin.Forms.ControlGallery.iOS
 			sl?.Children.Add(uilabel);
 
 			// Create and add a native Button 
-			var uibutton = new UIButton(UIButtonType.RoundedRect);
+			var uibutton = new UIButton(UIButtonType.System);
 			uibutton.SetTitle("Toggle Text Amount", UIControlState.Normal);
 			uibutton.Font = UIFont.FromName("Helvetica", 14f);
 
@@ -304,7 +304,7 @@ namespace Xamarin.Forms.ControlGallery.iOS
 				Text = "DefaultText"
 			};
 
-			var uibuttonColor = new UIButton(UIButtonType.RoundedRect);
+			var uibuttonColor = new UIButton(UIButtonType.System);
 			uibuttonColor.SetTitle("Toggle Text Color Binding", UIControlState.Normal);
 			uibuttonColor.Font = UIFont.FromName("Helvetica", 14f);
 			uibuttonColor.TouchUpInside += (sender, args) => uilabel.TextColor = UIColor.Blue;
@@ -347,7 +347,7 @@ namespace Xamarin.Forms.ControlGallery.iOS
 		public void StartPressed40911()
 		{
 			var loginViewController = new UIViewController { View = { BackgroundColor = UIColor.White } };
-			var button = UIButton.FromType(UIButtonType.RoundedRect);
+			var button = UIButton.FromType(UIButtonType.System);
 			button.SetTitle("Login", UIControlState.Normal);
 			button.Frame = new CGRect(20, 100, 200, 44);
 			loginViewController.View.AddSubview(button);
diff --git a/Xamarin.Forms.ControlGallery.iOS/CustomRenderer40251.cs b/Xamarin.Forms.ControlGallery.iOS/CustomRenderer40251.cs
new file mode 100644
index 00000000..19ebbb76
--- /dev/null
+++ b/Xamarin.Forms.ControlGallery.iOS/CustomRenderer40251.cs
@@ -0,0 +1,60 @@
+using UIKit;
+using Xamarin.Forms.Platform.iOS;
+using Xamarin.Forms;
+using System.Collections.Generic;
+using Xamarin.Forms.ControlGallery.iOS;
+using Xamarin.Forms.Controls.Issues;
+
+[assembly: ExportRenderer(typeof(Button), typeof(CustomRenderer40251))]
+namespace Xamarin.Forms.ControlGallery.iOS
+{
+	public class CustomRenderer40251 : ButtonRenderer
+	{
+		Dictionary<string, object> originalValues = new Dictionary<string, object>();
+
+		public CustomRenderer40251()
+		{
+			if (TestPage40251.Arg == "TitleColor")
+			{
+				originalValues.Add("TitleColor", UIButton.Appearance.TitleColor(UIControlState.Normal));
+				UIButton.Appearance.SetTitleColor(UIColor.Red, UIControlState.Normal);
+			}
+			else if (TestPage40251.Arg == "TitleShadowColor")
+			{
+				originalValues.Add("TitleShadowColor", UIButton.Appearance.TitleShadowColor(UIControlState.Normal));
+				UIButton.Appearance.SetTitleShadowColor(UIColor.White, UIControlState.Normal);
+			}
+			else if (TestPage40251.Arg == "BackgroundImage")
+			{
+				originalValues.Add("BackgroundImage", UIButton.Appearance.BackgroundImageForState(UIControlState.Normal));
+				UIButton.Appearance.SetBackgroundImage(new UIImage("Intranet-icon.png"), UIControlState.Normal);
+			}
+		}
+
+		protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
+		{
+			base.OnElementChanged(e);
+
+			if (e.NewElement != null)
+			{
+				if (Control != null)
+					Control.TitleShadowOffset = new CoreGraphics.CGSize(2, 2);
+			}
+		}
+
+		protected override void Dispose(bool disposing)
+		{
+			if (disposing)
+			{
+				if (TestPage40251.Arg == "TitleColor")
+					UIButton.Appearance.SetTitleColor(originalValues["TitleColor"] as UIColor, UIControlState.Normal);
+				else if (TestPage40251.Arg == "TitleShadowColor")
+					UIButton.Appearance.SetTitleShadowColor(originalValues["TitleShadowColor"] as UIColor, UIControlState.Normal);
+				else if (TestPage40251.Arg == "BackgroundImage")
+					UIButton.Appearance.SetBackgroundImage(originalValues["BackgroundImage"] as UIImage, UIControlState.Normal);
+			}
+
+			base.Dispose(disposing);
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.ControlGallery.iOS/Xamarin.Forms.ControlGallery.iOS.csproj b/Xamarin.Forms.ControlGallery.iOS/Xamarin.Forms.ControlGallery.iOS.csproj
index a601b513..0810383a 100644
--- a/Xamarin.Forms.ControlGallery.iOS/Xamarin.Forms.ControlGallery.iOS.csproj
+++ b/Xamarin.Forms.ControlGallery.iOS/Xamarin.Forms.ControlGallery.iOS.csproj
@@ -160,6 +160,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="BrokenNativeControl.cs" />
+    <Compile Include="CustomRenderer40251.cs" />
     <Compile Include="Main.cs" />
     <Compile Include="AppDelegate.cs" />
     <None Include="app.config" />
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla40251.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla40251.cs
new file mode 100644
index 00000000..64e9f667
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla40251.cs
@@ -0,0 +1,113 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 40251, "Cannot style Buttons natively using UIButton.Appearance", PlatformAffected.iOS)]
+	public class Bugzilla40251 : TestNavigationPage // or TestMasterDetailPage, etc ...
+	{
+		protected override void Init()
+		{
+			PushAsync(new LandingPage40251());
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class LandingPage40251 : ContentPage
+	{
+		public LandingPage40251()
+		{
+			var stackLayout = new StackLayout
+			{
+				Orientation = StackOrientation.Vertical,
+				Spacing = 20,
+				VerticalOptions = LayoutOptions.Center
+			};
+
+			var label0 = new Label
+			{
+				Text = "Each label below will update UIButton.Appearance proxy. When you remove the page from the stack, the original value will be set again.",
+				HorizontalTextAlignment = TextAlignment.Center
+			};
+			stackLayout.Children.Add(label0);
+
+			var label1 = new Label
+			{
+				Text = "TitleColor",
+				HorizontalTextAlignment = TextAlignment.Center
+			};
+			var t1 = new TapGestureRecognizer();
+			t1.Tapped += T_Tapped;
+			label1.GestureRecognizers.Add(t1);
+			stackLayout.Children.Add(label1);
+
+			var label2 = new Label
+			{
+				Text = "TitleShadowColor",
+				HorizontalTextAlignment = TextAlignment.Center
+			};
+			var t2 = new TapGestureRecognizer();
+			t2.Tapped += T_Tapped2;
+			label2.GestureRecognizers.Add(t2);
+			stackLayout.Children.Add(label2);
+
+			var label3 = new Label
+			{
+				Text = "BackgroundImage",
+				HorizontalTextAlignment = TextAlignment.Center
+			};
+			var t3 = new TapGestureRecognizer();
+			t3.Tapped += T_Tapped3;
+			label3.GestureRecognizers.Add(t3);
+			stackLayout.Children.Add(label3);
+
+			Content = stackLayout;
+		}
+
+		private async void T_Tapped(object sender, EventArgs e)
+		{
+			await Navigation.PushAsync(new TestPage40251("TitleColor"));
+		}
+
+		private async void T_Tapped2(object sender, EventArgs e)
+		{
+			await Navigation.PushAsync(new TestPage40251("TitleShadowColor"));
+		}
+
+		private async void T_Tapped3(object sender, EventArgs e)
+		{
+			await Navigation.PushAsync(new TestPage40251("BackgroundImage"));
+		}
+	}
+
+	[Preserve(AllMembers = true)]
+	public class TestPage40251 : ContentPage
+	{
+		public static string Arg;
+
+		public TestPage40251(string arg)
+		{
+			Arg = arg;
+
+			Content = new ContentView
+			{
+				Content = new Button
+				{
+					HorizontalOptions = LayoutOptions.Center,
+					VerticalOptions = LayoutOptions.Center,
+					Text = "Button",
+					BackgroundColor = Color.Black,
+					WidthRequest = 250,
+					HeightRequest = 50
+				}
+			};
+		}
+	}
+}
\ 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 23fc5381..d8b688dd 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
@@ -116,6 +116,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla40173.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla39821.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla40185.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla40251.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla40333.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla31806.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla40408.cs" />
diff --git a/Xamarin.Forms.Platform.iOS/Renderers/ButtonRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/ButtonRenderer.cs
index dbdcb241..dd25e635 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/ButtonRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/ButtonRenderer.cs
@@ -23,6 +23,8 @@ namespace Xamarin.Forms.Platform.iOS
 		// but under iOS that suggestion won't work
 		readonly nfloat _minimumButtonHeight = 44; // Apple docs
 
+		static readonly UIControlState[] s_controlStates = { UIControlState.Normal, UIControlState.Highlighted, UIControlState.Disabled };
+
 		public override SizeF SizeThatFits(SizeF size)
 		{
 			var result = base.SizeThatFits(size);
@@ -54,10 +56,12 @@ namespace Xamarin.Forms.Platform.iOS
 			{
 				if (Control == null)
 				{
-					SetNativeControl(new UIButton(UIButtonType.RoundedRect));
+					SetNativeControl(new UIButton(UIButtonType.System));
 
 					Debug.Assert(Control != null, "Control != null");
 
+					SetControlPropertiesFromProxy();
+
 					_buttonTextColorDefaultNormal = Control.TitleColor(UIControlState.Normal);
 					_buttonTextColorDefaultHighlighted = Control.TitleColor(UIControlState.Highlighted);
 					_buttonTextColorDefaultDisabled = Control.TitleColor(UIControlState.Disabled);
@@ -89,7 +93,7 @@ namespace Xamarin.Forms.Platform.iOS
 			else if (e.PropertyName == Button.ImageProperty.PropertyName)
 				UpdateImage();
 		}
-
+    
 		protected override void SetAccessibilityLabel()
 		{
 			// If we have not specified an AccessibilityLabel and the AccessibiltyLabel is current bound to the Title,
@@ -104,6 +108,16 @@ namespace Xamarin.Forms.Platform.iOS
 
 			base.SetAccessibilityLabel();
 		}
+		
+		void SetControlPropertiesFromProxy()
+		{
+			foreach (UIControlState uiControlState in s_controlStates)
+			{
+				Control.SetTitleColor(UIButton.Appearance.TitleColor(uiControlState), uiControlState); // if new values are null, old values are preserved.
+				Control.SetTitleShadowColor(UIButton.Appearance.TitleShadowColor(uiControlState), uiControlState);
+				Control.SetBackgroundImage(UIButton.Appearance.BackgroundImageForState(uiControlState), uiControlState);
+			}
+		}
 
 		void OnButtonTouchUpInside(object sender, EventArgs eventArgs)
 		{
@@ -198,9 +212,7 @@ namespace Xamarin.Forms.Platform.iOS
 		void ClearEdgeInsets(UIButton button)
 		{
 			if (button == null)
-			{
 				return;
-			}
 
 			Control.ImageEdgeInsets = new UIEdgeInsets(0, 0, 0, 0);
 			Control.TitleEdgeInsets = new UIEdgeInsets(0, 0, 0, 0);
@@ -210,9 +222,7 @@ namespace Xamarin.Forms.Platform.iOS
 		void ComputeEdgeInsets(UIButton button, Button.ButtonContentLayout layout)
 		{
 			if (button?.ImageView?.Image == null || string.IsNullOrEmpty(button.TitleLabel?.Text))
-			{
 				return;
-			}
 
 			var position = layout.Position;
 			var spacing = (nfloat)(layout.Spacing / 2);
@@ -264,4 +274,4 @@ namespace Xamarin.Forms.Platform.iOS
 			button.TitleEdgeInsets = new UIEdgeInsets(titleVertOffset, -horizontalTitleOffset, -titleVertOffset, horizontalTitleOffset);
 		}
 	}
-}
\ No newline at end of file
+}