如何在CAShapeLayer中将填充仅添加到UIBezierPath矩形的外部？

import UIKit

// 创建一个矩形的UIBezierPath
let rect = CGRect(x: 50, y: 50, width: 200, height: 100)
let path = UIBezierPath(rect: rect)

// 创建CAShapeLayer并设置路径
let shapeLayer = CAShapeLayer()
shapeLayer.path = path.cgPath

// 设置填充颜色
shapeLayer.fillColor = UIColor.red.cgColor

// 设置fillRule属性为kCAFillRuleNonZero
shapeLayer.fillRule = kCAFillRuleNonZero

// 添加到视图中显示
let view = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 200))
view.layer.addSublayer(shapeLayer)

// 在UIBezierPath矩形的外部添加一个小圆形
let circlePath = UIBezierPath(arcCenter: CGPoint(x: 150, y: 175), radius: 25, startAngle: 0, endAngle: CGFloat.pi * 2, clockwise: true)
circlePath.append(path)

// 创建另一个CAShapeLayer并设置路径
let circleShapeLayer = CAShapeLayer()
circleShapeLayer.path = circlePath.cgPath

// 设置填充颜色
circleShapeLayer.fillColor = UIColor.blue.cgColor

// 设置fillRule属性为kCAFillRuleNonZero
circleShapeLayer.fillRule = kCAFillRuleNonZero

// 添加到视图中显示
view.layer.addSublayer(circleShapeLayer)