UIView with border width, border color, corner radius

UIViewDecoration

import UIKit

protocol Decorating {
    var borderWidth: CGFloat {get set}
    var cornerRadius: CGFloat {get set}
    var borderColor: UIColor {get set}
    var shadowOffset: CGSize {get set}
}

extension Decorating where Self: UIView {
    var cornerRadius: CGFloat {
        get {
            return self.layer.cornerRadius
        }
        set {
            let rectShape = CAShapeLayer()
            rectShape.bounds = self.frame
            rectShape.position = self.center
            rectShape.path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: [.bottomLeft , .bottomRight , .topLeft], cornerRadii: CGSize(width: 20, height: 20)).cgPath

            self.layer.cornerRadius = newValue
            self.layer.masksToBounds = true
        }
    }
    
    var borderWidth: CGFloat {
        get {
            return self.layer.borderWidth
        }
        set {
            self.layer.borderWidth = newValue
        }
    }
    
    var borderColor: UIColor {
        get {
            return UIColor(cgColor: self.layer.borderColor!)
        }
        set {
            self.layer.borderColor = newValue.cgColor
        }
    }
    
    var shadowOffset: CGSize {
        get {
            return self.layer.shadowOffset
        }
        set {
            self.layer.shadowOffset = newValue
        }
    }

    var shadowColor: CGColor? {
        get {
            return self.layer.shadowColor
        }
        set {
            layer.shadowColor = newValue
        }
    }
    
    func addDropShadow(shadowColor: CGColor = UIColor.black.cgColor,
                       shadowOffset: CGSize = CGSize(width: 1.0, height: 2.0),
                       shadowOpacity: Float = 0.75,
                       shadowRadius: CGFloat = 3.0) {
        layer.shadowColor = shadowColor
        layer.shadowOffset = shadowOffset
        layer.shadowOpacity = shadowOpacity
        layer.shadowRadius = shadowRadius
    }
}

extension UIView: Decorating {
    @IBInspectable var shadow: Bool {
        get {
            return layer.shadowOpacity > 0.0
        }
        set {
            if newValue == true {
                self.addDropShadow()
            }
        }
    }
    
    @IBInspectable var cornerRadius: CGFloat {
        get {
            return self.layer.cornerRadius
        }
        set {
            self.layer.cornerRadius = newValue
            // Don't touch the masksToBound property if a shadow is needed in addition to the cornerRadius
            if shadow == false {
                self.layer.masksToBounds = true
            }
        }
    }
    
    func roundCorners(corners:UIRectCorner, radius:CGFloat) {
        if #available(iOS 11.0, *) {
            clipsToBounds = true
            layer.cornerRadius = radius
            layer.maskedCorners = CACornerMask(rawValue: corners.rawValue)
        } else {
            let cornerPath = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
            let maskLayer = CAShapeLayer()
            maskLayer.path = cornerPath.cgPath
            layer.mask = maskLayer
        }
    }
}