在第一次滚动PageViewController之前,UIImageView掩码层不会从角落来

我解决了问题

    path.move(to: .zero)
    /* THIS HELPLS ME */ path.addLine(to: CGPoint(x: 0  , y: self.imgView.frame.height  -  imageCutAwayPart / 2 ))
    path.addLine(to: CGPoint(x: self.imgView.frame.width   , y: self.imgView.frame.height - imageCutAwayPart))
    path.addLine(to: CGPoint(x: self.imgView.frame.width, y: 0))

但我不明白我为什么要搬家 CGPoint(x: 0 , y: self.imgView.frame.height - imageCutAwayPart / 2 ) 而不是这个 CGPoint(x: 0 , y: self.imgView.frame.height)

编辑

故事中有个愚蠢但聪明的错误

错误是有包含屏幕截图中显示的标签的UIView。可见的部分是UIView,我认为它的掩蔽工作不正常。仍然有一个问题,第一次在pageview控制器掩码是不正确的,但滚动一次后,它是完美的。

EDIT2感谢@DonMag

class CutOfImageView:UIImageView {
    let imageCutAwayPart:CGFloat = 80
    let maskLayer = CAShapeLayer()

    override func layoutSubviews() {
        super.layoutSubviews()
        self.setupImageCutPath()
        self.layer.mask = self.maskLayer

    }

    private func setupImageCutPath () {
        let path = UIBezierPath()
        path.move(to: .zero)
        path.addLine(to: CGPoint(x: 0  , y: self.frame.height ))
        path.addLine(to: CGPoint(x: self.frame.width   , y: self.frame.height - imageCutAwayPart))
        path.addLine(to: CGPoint(x: self.frame.width, y: 0))
        path.close()
        self.maskLayer.path = path.cgPath



    }
}