Swift - 圆角半径和阴影问题

为了扩展 Imanou 的帖子，可以在自定义按钮类中以编程方式添加阴影层

@IBDesignable class CustomButton: UIButton {
    var shadowAdded: Bool = false

    @IBInspectable var cornerRadius: CGFloat = 0 {
        didSet {
            layer.cornerRadius = cornerRadius
            layer.masksToBounds = cornerRadius > 0
        }
    }

    override func drawRect(rect: CGRect) {
        super.drawRect(rect)

        if shadowAdded { return }
        shadowAdded = true

        let shadowLayer = UIView(frame: self.frame)
        shadowLayer.backgroundColor = UIColor.clearColor()
        shadowLayer.layer.shadowColor = UIColor.darkGrayColor().CGColor
        shadowLayer.layer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: self.cornerRadius).CGPath
        shadowLayer.layer.shadowOffset = CGSize(width: 1.0, height: 1.0)
        shadowLayer.layer.shadowOpacity = 0.5
        shadowLayer.layer.shadowRadius = 1
        shadowLayer.layer.masksToBounds = true
        shadowLayer.clipsToBounds = false

        self.superview?.addSubview(shadowLayer)
        self.superview?.bringSubviewToFront(self)
    }
}

---

获得更多可用和一致按钮的另一种方法。

斯威夫特 2：

func getImageWithColor(color: UIColor, size: CGSize, cornerRadius:CGFloat) -> UIImage {
    let rect = CGRectMake(0, 0, size.width, size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 1)
    UIBezierPath(
        roundedRect: rect,
        cornerRadius: cornerRadius
        ).addClip()
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}

let button = UIButton(type: .Custom)
button.frame = CGRectMake(20, 20, 200, 50)
button.setTitle("My Button", forState: UIControlState.Normal)
button.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
self.addSubview(button)

let image = getImageWithColor(UIColor.whiteColor(), size: button.frame.size, cornerRadius: 5)
button.setBackgroundImage(image, forState: UIControlState.Normal)

button.layer.shadowRadius = 5
button.layer.shadowColor = UIColor.blackColor().CGColor
button.layer.shadowOpacity = 0.5
button.layer.shadowOffset = CGSizeMake(0, 1)
button.layer.masksToBounds = false

斯威夫特 3：

func getImageWithColor(_ color: UIColor, size: CGSize, cornerRadius:CGFloat) -> UIImage? {
    let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    color.setFill()
    UIBezierPath(roundedRect: rect, cornerRadius: cornerRadius).addClip()
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return image
}

let button = UIButton(type: .custom)
button.frame = CGRect(x:20, y:20, width:200, height:50)
button.setTitle("My Button", for: .normal)
button.setTitleColor(UIColor.black, for: .normal)
self.addSubview(button)

if let image = getImageWithColor(UIColor.white, size: button.frame.size, cornerRadius: 5) {
    button.setBackgroundImage(image, for: .normal)
}

button.layer.shadowRadius = 5
button.layer.shadowColor = UIColor.black.cgColor
button.layer.shadowOpacity = 0.5
button.layer.shadowOffset = CGSize(width:0, height:1)
button.layer.masksToBounds = false

---

Swift 5 & 不需要“UIBezierPath”

    view.layer.cornerRadius = 15
    view.clipsToBounds = true
    view.layer.masksToBounds = false
    view.layer.shadowRadius = 7
    view.layer.shadowOpacity = 0.6
    view.layer.shadowOffset = CGSize(width: 0, height: 5)
    view.layer.shadowColor = UIColor.red.cgColor

---

重构 this 以支持任何视图。从这个子类你的视图，它应该有圆角。如果您将 UIVisualEffectView 之类的内容作为子视图添加到此视图，您可能需要在该 UIVisualEffectView 上使用相同的圆角，否则它不会有圆角。

https://i.stack.imgur.com/ztnb4.png

/// Inspiration: https://stackoverflow.com/a/25475536/129202
class ViewWithRoundedcornersAndShadow: UIView {
    private var theShadowLayer: CAShapeLayer?

    override func layoutSubviews() {
        super.layoutSubviews()

        if self.theShadowLayer == nil {
            let rounding = CGFloat.init(22.0)

            let shadowLayer = CAShapeLayer.init()
            self.theShadowLayer = shadowLayer
            shadowLayer.path = UIBezierPath.init(roundedRect: bounds, cornerRadius: rounding).cgPath
            shadowLayer.fillColor = UIColor.clear.cgColor

            shadowLayer.shadowPath = shadowLayer.path
            shadowLayer.shadowColor = UIColor.black.cgColor
            shadowLayer.shadowRadius = CGFloat.init(3.0)
            shadowLayer.shadowOpacity = Float.init(0.2)
            shadowLayer.shadowOffset = CGSize.init(width: 0.0, height: 4.0)

            self.layer.insertSublayer(shadowLayer, at: 0)
        }
    }
}

---

带阴影的拐角半径

简短而简单的方法！！！！

extension CALayer {
    func applyCornerRadiusShadow(
        color: UIColor = .black,
        alpha: Float = 0.5,
        x: CGFloat = 0,
        y: CGFloat = 2,
        blur: CGFloat = 4,
        spread: CGFloat = 0,
        cornerRadiusValue: CGFloat = 0)
    {
        cornerRadius = cornerRadiusValue
        shadowColor = color.cgColor
        shadowOpacity = alpha
        shadowOffset = CGSize(width: x, height: y)
        shadowRadius = blur / 2.0
        if spread == 0 {
            shadowPath = nil
        } else {
            let dx = -spread
            let rect = bounds.insetBy(dx: dx, dy: dx)
            shadowPath = UIBezierPath(rect: rect).cgPath
        }
    }

代码的使用

btn.layer.applyCornerRadiusShadow(color: .black, 
                            alpha: 0.38, 
                            x: 0, y: 3, 
                            blur: 10, 
                            spread: 0, 
                            cornerRadiusValue: 24)

不需要 maskToBound

请验证 clipsToBounds 是否为假。

输出

https://i.stack.imgur.com/uy1Tx.png

---

为了改进 PiterPan 的答案并在 Swift 3 中使用圆形按钮显示真实的阴影（不仅仅是没有模糊的背景）：

override func viewDidLoad() {
    super.viewDidLoad()
    myButton.layer.masksToBounds = false
    myButton.layer.cornerRadius = myButton.frame.height/2
    myButton.clipsToBounds = true
}

override func viewDidLayoutSubviews() {
    addShadowForRoundedButton(view: self.view, button: myButton, opacity: 0.5)
}

func addShadowForRoundedButton(view: UIView, button: UIButton, opacity: Float = 1) {
    let shadowView = UIView()
    shadowView.backgroundColor = UIColor.black
    shadowView.layer.opacity = opacity
    shadowView.layer.shadowRadius = 5
    shadowView.layer.shadowOpacity = 0.35
    shadowView.layer.shadowOffset = CGSize(width: 0, height: 0)
    shadowView.layer.cornerRadius = button.bounds.size.width / 2
    shadowView.frame = CGRect(origin: CGPoint(x: button.frame.origin.x, y: button.frame.origin.y), size: CGSize(width: button.bounds.width, height: button.bounds.height))
    self.view.addSubview(shadowView)
    view.bringSubview(toFront: button)
}

---

2020 语法的准确解决方案

import UIKit
class ColorAndShadowButton: UIButton {
    override init(frame: CGRect) { super.init(frame: frame), common() }
    required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder), common() }
    private func common() {
        // UIButton is tricky: you MUST set the clear bg in bringup;  NOT in layout
        backgroundColor = .clear
        clipsToBounds = false
        self.layer.insertSublayer(colorAndShadow, below: layer)
    }
    
   lazy var colorAndShadow: CAShapeLayer = {
        let s = CAShapeLayer()
        // set your button color HERE (NOT on storyboard)
        s.fillColor = UIColor.black.cgColor
        // now set your shadow color/values
        s.shadowColor = UIColor.red.cgColor
        s.shadowOffset = CGSize(width: 0, height: 10)
        s.shadowOpacity = 1
        s.shadowRadius = 10
        // now add the shadow
        layer.insertSublayer(s, at: 0)
        return s
    }()
    
    override func layoutSubviews() {
        super.layoutSubviews()
        // you MUST layout these two EVERY layout cycle:
        colorAndShadow.frame = bounds
        colorAndShadow.path = UIBezierPath(roundedRect: bounds, cornerRadius: 12).cgPath
    }
}

请注意，这里非常古老的最佳答案是正确的，但有一个严重错误

请注意，不幸的是 UIButton 与 iOS 中的 UIView 完全不同。

由于 iOS 中的一个奇怪行为，您必须在初始化时设置背景颜色（在这种情况下当然必须清楚），而不是在布局中。您可以在情节提要中将其设置为清晰（但您通常单击它以使其成为纯色，以便在情节提要中工作时可以看到它。）

一般来说，阴影/圆角的组合在 iOS 中是一个真正的痛苦。类似的解决方案：

https://stackoverflow.com/a/57465440/294884 - 图像 + 圆角 + 阴影
https://stackoverflow.com/a/41553784/294884 - 两角问题
https://stackoverflow.com/a/59092828/294884 - “阴影 + 孔”或“发光盒”问题
https://stackoverflow.com/a/57400842/294884 - “边界与间隙”问题
https://stackoverflow.com/a/57514286/294884 - 基本的“添加”贝塞尔曲线

---

投影和角半径的扩展

extension UIView {

func dropShadow(color: UIColor, opacity: Float = 0.5, offSet: CGSize, shadowRadius: CGFloat = 1, scale: Bool = true, cornerRadius: CGFloat) {
    let shadowLayer = CAShapeLayer()
    shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius).cgPath
    shadowLayer.fillColor = UIColor.white.cgColor
    shadowLayer.shadowColor = color.cgColor
    shadowLayer.shadowPath = shadowLayer.path
    shadowLayer.shadowOffset = offSet
    shadowLayer.shadowOpacity = opacity
    shadowLayer.shadowRadius = shadowRadius
    layer.insertSublayer(shadowLayer, at: 0)
}

}

---

这是可行的解决方案！

extension UIView {

    func applyShadowWithCornerRadius(color:UIColor, opacity:Float, radius: CGFloat, edge:AIEdge, shadowSpace:CGFloat)    {

        var sizeOffset:CGSize = CGSize.zero
        switch edge {
        case .Top:
            sizeOffset = CGSize(width: 0, height: -shadowSpace)
        case .Left:
            sizeOffset = CGSize(width: -shadowSpace, height: 0)
        case .Bottom:
            sizeOffset = CGSize(width: 0, height: shadowSpace)
        case .Right:
            sizeOffset = CGSize(width: shadowSpace, height: 0)


        case .Top_Left:
            sizeOffset = CGSize(width: -shadowSpace, height: -shadowSpace)
        case .Top_Right:
            sizeOffset = CGSize(width: shadowSpace, height: -shadowSpace)
        case .Bottom_Left:
            sizeOffset = CGSize(width: -shadowSpace, height: shadowSpace)
        case .Bottom_Right:
            sizeOffset = CGSize(width: shadowSpace, height: shadowSpace)


        case .All:
            sizeOffset = CGSize(width: 0, height: 0)
        case .None:
            sizeOffset = CGSize.zero
        }

        self.layer.cornerRadius = self.frame.size.height / 2
        self.layer.masksToBounds = true;

        self.layer.shadowColor = color.cgColor
        self.layer.shadowOpacity = opacity
        self.layer.shadowOffset = sizeOffset
        self.layer.shadowRadius = radius
        self.layer.masksToBounds = false

        self.layer.shadowPath = UIBezierPath(roundedRect:self.bounds, cornerRadius:self.layer.cornerRadius).cgPath
    }
}

enum AIEdge:Int {
    case
    Top,
    Left,
    Bottom,
    Right,
    Top_Left,
    Top_Right,
    Bottom_Left,
    Bottom_Right,
    All,
    None
}

最后，按如下方式应用具有角半径调用的阴影：

viewRounded.applyShadowWithCornerRadius(color: .gray, opacity: 1, radius: 15, edge: AIEdge.All, shadowSpace: 15)

结果图像

https://i.stack.imgur.com/vKBqX.png

更新：如果您没有看到预期的输出，请尝试从主线程调用扩展方法，这肯定会起作用！

DispatchQueue.main.async {
    viewRounded.applyShadowWithCornerRadius(color: .gray, opacity: 1, radius: 15, edge: AIEdge.All, shadowSpace: 15)
}

---

如果有人需要在 Swift 3.0 中为圆形按钮添加阴影，这是一个很好的方法。

func addShadowForRoundedButton(view: UIView, button: UIButton, shadowColor: UIColor, shadowOffset: CGSize, opacity: Float = 1) {
    let shadowView = UIView()
    shadowView.backgroundColor = shadowColor
    shadowView.layer.opacity = opacity
    shadowView.layer.cornerRadius = button.bounds.size.width / 2
    shadowView.frame = CGRect(origin: CGPoint(x: button.frame.origin.x + shadowOffset.width, y: button.frame.origin.y + shadowOffset.height), size: CGSize(width: button.bouds.width, height: button.bounds.height))
    self.view.addSubview(shadowView)
    view.bringSubview(toFront: button)
}

在 func viewDidLayoutSubviews() 中使用此方法，如下所示：

override func viewDidLayoutSubviews() {
    addShadowForRoundedButton(view: self.view, button: button, shadowColor: .black, shadowOffset: CGSize(width: 2, height: 2), opacity: 0.5)
}

https://i.stack.imgur.com/hkS6E.png

---

您可以创建一个协议并使其符合您的 UIView、UIButton、Cell 或任何您想要的内容：

protocol RoundedShadowable: class {
    var shadowLayer: CAShapeLayer? { get set }
    var layer: CALayer { get }
    var bounds: CGRect { get }
}
​
extension RoundedShadowable {
    func applyShadowOnce(withCornerRadius cornerRadius: CGFloat, andFillColor fillColor: UIColor) {
        if self.shadowLayer == nil {
            let shadowLayer = CAShapeLayer()
            shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius).cgPath
            shadowLayer.fillColor = fillColor.cgColor
            shadowLayer.shadowColor = UIColor.black.cgColor
            shadowLayer.shadowPath = shadowLayer.path
            shadowLayer.shadowOffset = CGSize(width: 0.0, height: 2.0)
            shadowLayer.shadowOpacity = 0.2
            shadowLayer.shadowRadius = 3
            self.layer.insertSublayer(shadowLayer, at: 0)
            self.shadowLayer = shadowLayer
        }
    }
}
​
class RoundShadowView: UIView, RoundedShadowable {

    var shadowLayer: CAShapeLayer?
    private let cornerRadius: CGFloat
    private let fillColor: UIColor

    init(cornerRadius: CGFloat, fillColor: UIColor) {
        self.cornerRadius = cornerRadius
        self.fillColor = fillColor
        super.init(frame: .zero)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        self.applyShadowOnce(withCornerRadius: self.cornerRadius, andFillColor: self.fillColor)
    }
}
​
class RoundShadowButton: UIButton, RoundedShadowable {

    var shadowLayer: CAShapeLayer?
    private let cornerRadius: CGFloat
    private let fillColor: UIColor

    init(cornerRadius: CGFloat, fillColor: UIColor) {
        self.cornerRadius = cornerRadius
        self.fillColor = fillColor
        super.init(frame: .zero)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        self.applyShadowOnce(withCornerRadius: self.cornerRadius, andFillColor: self.fillColor)
    }
}

---