如何给 UIView 添加阴影？答案

【问题标题】：How to add shadow to UIView?如何给 UIView 添加阴影？
【发布时间】：2018-07-19 01:07:32
【问题描述】：

For UIView 我给出了两侧的圆角半径并添加了阴影。现在，我得到了两侧的圆角半径，而不是阴影。

这是我使用的代码：

@IBOutlet var myView: UIView!

override func viewDidLoad() {
    super.viewDidLoad()
   let shadowpath = UIBezierPath(roundedRect: CGRect(x: 0, y: 0, width: 
   myView.frame.height, height: myView.frame.height), byRoundingCorners: 
   [.topRight, .bottomRight], cornerRadii: CGSize(width: 58.0, height: 0.0))

    myView.layer.shadowColor = UIColor.black.cgColor
    myView.layer.shadowOffset = CGSize(width: 0.5, height: 0.4)  //Here you 
    control x and y
    myView.layer.shadowOpacity = 0.5
    myView.layer.shadowRadius = 5.0 //Here your control your blur
    myView.layer.masksToBounds =  false
    myView.layer.shadowPath = shadowpath.cgPath

截图：

【问题讨论】：

请显示该代码的其余部分。你也屏蔽图层吗？绘制圆角形状的代码在哪里？
期望什么？我看不出有什么问题。
@user28434 应为屏幕截图结果
好的，那么你能展示一下现在发生了什么吗？就像当前状态截图一样。
@user28434 是的，当然！

标签： ios swift swift3 uiview

【解决方案1】：

Swift 5+ 解决方案

extension UIView{
    func dropShadowWithCornerRaduis() {
        layer.masksToBounds = true
        layer.cornerRadius = 25
        layer.shadowColor = UIColor.gray.cgColor
        layer.shadowOpacity = 0.5
        layer.shadowOffset = CGSize(width: 0, height: 0)
        layer.shadowRadius = 1
        layer.shouldRasterize = true
        layer.rasterizationScale = UIScreen.main.scale
       
    }
}

用法

contentView.dropShadowWithCornerRaduis()

【讨论】：

【解决方案2】：

添加 Swift 5+ 解决方案：

let tempView = UIView(frame: CGRect(x: 0, y: -50, width: self.view.frame.size.width/1.4, height: 300))

//below is the code you need to add, adjust Opacity as needed
        tempView.layer.shadowColor = UIColor.black.cgColor
        tempView.layer.shadowOpacity = 0.8
        tempView.layer.shadowOffset = .zero
        tempView.layer.shadowRadius = 10

【讨论】：

【解决方案3】：

直接从情节提要中使用的简单扩展。斯威夫特 4+

@IBDesignable extension UIView {
    @IBInspectable var shadowColor: UIColor?{
        set {
            guard let uiColor = newValue else { return }
            layer.shadowColor = uiColor.cgColor
        }
        get{
            guard let color = layer.shadowColor else { return nil }
            return UIColor(cgColor: color)
        }
    }

    @IBInspectable var shadowOpacity: Float{
        set {
            layer.shadowOpacity = newValue
        }
        get{
            return layer.shadowOpacity
        }
    }

    @IBInspectable var shadowOffset: CGSize{
        set {
            layer.shadowOffset = newValue
        }
        get{
            return layer.shadowOffset
        }
    }

    @IBInspectable var shadowRadius: CGFloat{
        set {
            layer.shadowRadius = newValue
        }
        get{
            return layer.shadowRadius
        }
    }
}

【讨论】：

【解决方案4】：

我自己通过给 layerMaxXMinYCorner 和 layerMaxXMaxYCorner 找到了答案

   myView.clipsToBounds = true
    myView.layer.cornerRadius = 58
    if #available(iOS 11.0, *) {
        myView.layer.maskedCorners = [.layerMaxXMinYCorner, 
  .layerMaxXMaxYCorner ]
    } else {
        // Fallback on earlier versions
    }

    let shadowpath = UIBezierPath(roundedRect: self.myView.bounds, 
    byRoundingCorners: [.topRight, .bottomRight], cornerRadii: CGSize(width: 
   58.0, height: 0.0))



    myView.layer.shadowColor = UIColor.black.cgColor
    myView.layer.shadowOffset = CGSize(width: 1, height: 1)  //Here you 
    control x and y
    myView.layer.shadowOpacity = 0.5
    myView.layer.shadowRadius = 15 //Here your control your blur
    myView.layer.masksToBounds =  false
    myView.layer.shadowPath = shadowpath.cgPath

【讨论】：

【解决方案5】：

关键是使用“容器”视图...你添加一个“阴影层”作为容器视图的子层，并将蒙版视图添加为容器的子视图。

这是一个您可以在 Playground 中运行的示例，它将为您提供所展示的目标（您可能需要调整颜色值、阴影半径和偏移量）：

import UIKit
import PlaygroundSupport

class TestViewController : UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = UIColor.init(white: 0.8, alpha: 1.0)

        let myView = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        myView.backgroundColor = .white

        let mask = CAShapeLayer()

        let shadowpath = UIBezierPath(roundedRect: CGRect(x: 0, y: 0, width:
            myView.frame.height, height: myView.frame.height), byRoundingCorners:
            [.topRight, .bottomRight], cornerRadii: CGSize(width: 58.0, height: 0.0))

        mask.path = shadowpath.cgPath
        myView.layer.mask = mask

        let shadowLayer = CAShapeLayer()
        shadowLayer.frame = myView.bounds
        shadowLayer.path = shadowpath.cgPath
        shadowLayer.shadowOpacity = 0.5
        shadowLayer.shadowRadius = 5
        shadowLayer.shadowColor = UIColor(red: 0.2, green: 0.5, blue: 1.0, alpha: 1.0).cgColor
        shadowLayer.masksToBounds = false
        shadowLayer.shadowOffset = CGSize(width: 5.0, height: 1.0)

        let container = UIView(frame: CGRect(x: 40, y: 100, width: myView.bounds.width, height: myView.bounds.height))
        container.backgroundColor = .clear
        container.layer.addSublayer(shadowLayer)
        container.addSubview(myView)

        view.addSubview(container)

    }

}

let vc = TestViewController()
PlaygroundPage.current.liveView = vc

结果：

【讨论】：