[iOS] Clip Border content based on StrokeShape property

src/Core/src/Platform/iOS/ContentView.cs

@@ -1,11 +1,15 @@
 using System;
+using CoreAnimation;
 using CoreGraphics;
 using Microsoft.Maui.Graphics;
+using Microsoft.Maui.Graphics.Platform;
 
 namespace Microsoft.Maui.Platform
 {
 	public class ContentView : MauiView
 	{
+		IBorderStroke? _clip;
+		CAShapeLayer? _childMaskLayer;
 		internal event EventHandler? LayoutSubviewsChanged;
 
 		public override CGSize SizeThatFits(CGSize size)
@@ -32,7 +36,12 @@ public override void LayoutSubviews()
 			CrossPlatformMeasure?.Invoke(bounds.Width, bounds.Height);
 			CrossPlatformArrange?.Invoke(bounds);
 
-			LayoutSubviewsChanged?.Invoke(this, EventArgs.Empty);
+			if (ChildMaskLayer != null)
+				ChildMaskLayer.Frame = bounds;
+
+			SetClip();
+
+      LayoutSubviewsChanged?.Invoke(this, EventArgs.Empty);
 		}
 
 		public override void SetNeedsLayout()
@@ -43,5 +52,68 @@ public override void SetNeedsLayout()
 
 		internal Func<double, double, Size>? CrossPlatformMeasure { get; set; }
 		internal Func<Rect, Size>? CrossPlatformArrange { get; set; }
+
+		internal IBorderStroke? Clip
+		{
+			get { return _clip; }
+			set
+			{
+				_clip = value;
+
+				SetClip();
+			}
+		}
+
+		CAShapeLayer? ChildMaskLayer
+		{
+			get => _childMaskLayer;
+			set
+			{
+				var layer = GetChildLayer();
+
+				if (layer != null && _childMaskLayer != null)
+					layer.Mask = null;
+
+				_childMaskLayer = value;
+
+				if (layer != null)
+					layer.Mask = value;
+			}
+		}
+
+		CALayer? GetChildLayer()
+		{
+			if (Subviews.Length == 0)
+				return null;
+
+			var child = Subviews[0];
+
+			if (child.Layer == null || child.Layer.Sublayers == null)
+				return null;
+
+			return child.Layer;
+		}
+
+		void SetClip()
+		{
+			if (Subviews.Length == 0)
+				return;
+
+			var mask = ChildMaskLayer;
+
+			if (mask == null && Clip == null)
+				return;
+
+			mask ??= ChildMaskLayer = new CAShapeLayer();
+
+			var frame = Frame;
+
+			var bounds = new RectF(0, 0, (float)frame.Width, (float)frame.Height);
+
+			IShape? clipShape = Clip?.Shape;
+			var path = clipShape?.PathForBounds(bounds);
+			var nativePath = path?.AsCGPath();
+			mask.Path = nativePath;
+		}
 	}
 }

src/Core/src/Platform/iOS/StrokeExtensions.cs

@@ -135,7 +135,7 @@ internal static void UpdateMauiCALayer(this UIView platformView, IBorderStroke?
 				mauiCALayer.SetBorderWidth(border?.StrokeThickness ?? 0);
 				mauiCALayer.SetBorderDash(border?.StrokeDashPattern, border?.StrokeDashOffset ?? 0);
 				mauiCALayer.SetBorderMiterLimit(border?.StrokeMiterLimit ?? 0);
-				
+
 				if (border != null)
 				{
 					mauiCALayer.SetBorderLineJoin(border.StrokeLineJoin);
@@ -144,6 +144,9 @@ internal static void UpdateMauiCALayer(this UIView platformView, IBorderStroke?
 
 				mauiCALayer.SetBorderShape(border?.Shape);
 			}
+
+			if (platformView is ContentView contentView)
+				contentView.Clip = border;
 		}
 
 		internal static void UpdateMauiCALayer(this UIView view)