如何在顶部的UIView上应用向下曲线

class CurvedView: UIView {
    override func draw(_ rect: CGRect) {
        let path = UIBezierPath()
        path.move(to: CGPoint(x: 0, y: 0))
        path.addLine(to: CGPoint(x: rect.width, y: 0))
        path.addLine(to: CGPoint(x: rect.width, y: rect.height))
        path.addQuadCurve(to: CGPoint(x: 0, y: rect.height), controlPoint: CGPoint(x: rect.width/2, y: rect.height + 50))
        path.close()
        
        let shapeLayer = CAShapeLayer()
        shapeLayer.path = path.cgPath
        self.layer.mask = shapeLayer
    }
}

let curvedView = CurvedView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: 200))
view.addSubview(curvedView)