Swift 用UIBezierPath和CAShapeLayer给UIView画圆角、边、阴影。

一、绘制圆角

View的四个角可以绘制想要的圆角：
.allCorners 四个角都是圆角
.topLeft 上左
.topRight 上右
.bottomLeft 下左
.bottomRight 下右

 //画圆
 let maskPath = UIBezierPath.init(roundedRect: self.agreeButton.bounds, byRoundingCorners: .allCorners, cornerRadii: CGSize.init(width: 45/2, height: 45/2))

 let maskLayer = CAShapeLayer.init()
 maskLayer.frame = self.agreeButton.bounds
 maskLayer.path = maskPath2.cgPath
 self.agreeButton.layer.mask = maskLayer

绘制圆角效果图

二、绘制圆角的同时绘制边框

 //画圆的同时画边框
 let maskPath = UIBezierPath.init(roundedRect: self.refuseButton.bounds, byRoundingCorners: .allCorners, cornerRadii: CGSize.init(width: 45/2, height: 45/2))

 let maskLayer1 = CAShapeLayer.init()
 maskLayer1.frame = self.refuseButton.bounds
 maskLayer1.path = maskPath1.cgPath
 maskLayer1.strokeColor = UIColor.RGBToColor(86, 155, 213).cgColor
 maskLayer1.fillColor = UIColor.white.cgColor
 maskLayer1.lineWidth = 1
 self.refuseButton.layer.addSublayer(maskLayer1)

绘制圆角+边框效果图

三、绘制边框

//画边
 let linePath = UIBezierPath.init(rect: self.testView.bounds)
        
 let shapeLayer = CAShapeLayer()
 shapeLayer.frame = CGRect.init(x: 0, y:0, width: 100, height: 100)
 shapeLayer.path = linePath.cgPath
 shapeLayer.lineWidth = 1
 shapeLayer.strokeColor = UIColor.red.cgColor
 shapeLayer.fillColor = UIColor.clear.cgColor
 self.testView.layer.addSublayer(shapeLayer)

边框效果图

四、绘制圆角和阴影

用UIBezierPath给View画阴影，需要重写View的draw(_ rect: CGRect)方法

override func draw(_ rect: CGRect) {
      
        //画圆角和阴影
        let shadowPath = UIBezierPath(roundedRect: rect.insetBy(dx: 5, dy: 5), byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: 10, height: 10))
        let context = UIGraphicsGetCurrentContext()
        context?.setShadow(offset: CGSize(width: 5, height:5), blur: 5, color: UIColor.black.cgColor)
        UIColor.RGBToColor(86, 155, 213).setFill()
        shadowPath.fill()
       
    }

UIBezierPath画阴影效果图

用UIBezierPath同时要实现任意圆角+阴影，只能通过在draw(_ rect: CGRect)方法中实现，rect.insetBy(dx: 5, dy: 5)导致空件大小比实际上小，但是值为0时又没有阴影效果。

用layer属性设置阴影比用UIBezierPath的效果好