问为什么我的阴影层没有正确定位？

EN

import UIKit

@IBDesignable
class RoundedView: UIView {

    @IBInspectable var shadowColor : UIColor? {
        didSet {
            layer.shadowColor = shadowColor?.cgColor
            layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
        }
    }

    @IBInspectable var shadowOffset : CGSize = CGSize(width: 20, height: 20) {
        didSet {
            layer.shadowOffset = shadowOffset
            layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
        }
    }

    @IBInspectable var shadowRadius : CGFloat = 0.0 {
        didSet {
            layer.shadowRadius = shadowRadius
            layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
        }
    }

    @IBInspectable var shadowOpacity : Float = 1.0 {
        didSet {
            layer.shadowOpacity = shadowOpacity
            layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
        }
    }


}

shadowPath: 
    Path 0x60800022e040:
      moveto (0, 0)
        lineto (300, 0)
        lineto (300, 150)
        lineto (0, 150)
        closepath
self.bounds: 
    (0.0, 0.0, 300.0, 150.0)
self.frame: 
    (37.0, 268.5, 300.0, 150.0)