Question

如何向被路径遮盖的视图添加阴影？

layer具有mask属性，您可以像这样yourCustomView.layer.mask = somePath进行设置。但是如何添加也被layer.mask遮住的阴影？

Answer 1

我看到这个问题问了很多，答案到处都是，所以我想我可以把一个小记号集中起来。

基本上，当您要将阴影添加到用路径遮盖的视图中时，事情会变得很有趣。

这是我构建的扩展程序，可以处理所有问题，并且非常易于使用。 corners参数是为基本圆角设置而设置的，但是您可以将其替换为所需的任何UIBezierPath。

import UIKit

public extension UIView {
    /// You will probably need to call this from viewDidLayoutSubviews()
    func roundCorners(corners: UIRectCorner = .bottomRight, radius: CGFloat = 40) {
        layoutIfNeeded()

        let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
        let mask = CAShapeLayer()
        mask.path = path.cgPath
        self.layer.mask = mask
    }

    /// You will probably need to call this from viewDidLayoutSubviews()
    func roundCornersWithShadow(corners: UIRectCorner = .bottomRight, cornerRadius radius: Double = 40, shadowOpacity: Float = 0.5, shadowRadius: Double = 4, shadowOffset: CGSize = CGSize(width: 0, height: 2), shadowColor: UIColor = .black, maskName: String = "mask", shadowName: String = "shadow") {

        layoutIfNeeded()

        let path = UIBezierPath(roundedRect: bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius)).cgPath

        let maskLayer = CAShapeLayer()
        maskLayer.frame = bounds
        maskLayer.path = path
        layer.mask = maskLayer
        layer.name = maskName

        if let subLayers = superview?.layer.sublayers {
            for layer in subLayers where layer.name == shadowName { layer.removeFromSuperlayer() }
        }

        let shadowLayer = CAShapeLayer()
        shadowLayer.name = shadowName
        shadowLayer.path = path
        shadowLayer.frame = frame

        shadowLayer.shadowOpacity = shadowOpacity
        shadowLayer.shadowRadius = CGFloat(shadowRadius)
        shadowLayer.shadowColor = shadowColor.cgColor
        shadowLayer.shadowOffset = shadowOffset

        superview?.layer.insertSublayer(shadowLayer, below: layer)
    }
}

然后使用类似于：

override func viewDidLayoutSubviews() {
    ...
    yourView.roundCornersWithShadow(corners: [.bottomRight, .bottomLeft, .topRight, .topLeft]) // Use whatever corners you want.
}

如何在用路径遮罩的视图中添加阴影

1 个答案: