问如何使用蒙版在视图中添加阴影

EN

    [![enter image description here][1]][1]let trapezoidPath = UIBezierPath()
    trapezoidPath.move(to: CGPoint(x: 0, y: 0))
    trapezoidPath.addLine(to: CGPoint(x: Constants.padding, y: bounds.maxY - 10))
    trapezoidPath.addLine(to: CGPoint(x: titleLabel.bounds.width + Constants.padding, y: bounds.maxY - 10))
    trapezoidPath.addLine(to: CGPoint(x: titleLabel.bounds.width + 2 * Constants.padding, y: 0))

    let trapezoidLayer = CAShapeLayer()
    trapezoidLayer.path = trapezoidPath.cgPath
    
    whiteView.layer.shadowPath = UIBezierPath(roundedRect: trapezoidPath.bounds, cornerRadius: whiteView.layer.cornerRadius).cgPath
    whiteView.layer.shadowRadius = 15
    whiteView.layer.shadowOffset = .zero
    whiteView.layer.shadowOpacity = 0.4
    whiteView.layer.masksToBounds = false
    whiteView.layer.shadowColor = UIColor.red.cgColor

    whiteView.layer.mask = trapezoidLayer