如何添加内阴影到圆角的UIView

import UIKit

class ShadowView: UIView {
    override func layoutSubviews() {
        super.layoutSubviews()
        
        // 设置圆角
        layer.cornerRadius = bounds.height / 2
        
        // 创建阴影Layer
        let shadowLayer = CALayer()
        shadowLayer.frame = bounds
        shadowLayer.backgroundColor = UIColor.white.cgColor
        shadowLayer.cornerRadius = layer.cornerRadius
        shadowLayer.shadowColor = UIColor.black.cgColor
        shadowLayer.shadowOpacity = 0.5
        shadowLayer.shadowOffset = CGSize(width: 0, height: 2)
        shadowLayer.shadowRadius = 4
        shadowLayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: layer.cornerRadius).cgPath
        
        // 添加阴影Layer
        layer.addSublayer(shadowLayer)
    }
}