Add border width, border colour and radius to UIView as inspectable properties, accessible in Interface Builder

DesignableView.swift

import UIKit

@IBDesignable
extension UIView {
	@IBInspectable var cornerRadius: CGFloat {
		get {
			return layer.cornerRadius
		}
		set {
			layer.cornerRadius = newValue
			layer.masksToBounds = newValue > 0
		}
	}
	@IBInspectable var borderWidth: CGFloat {
		get {
			return layer.borderWidth
		}
		set {
			layer.borderWidth = newValue
		}
	}
	@IBInspectable var borderColor: UIColor? {
		get {
			return UIColor(cgColor: layer.borderColor!)
		}
		set {
			layer.borderColor = newValue?.cgColor
		}
	}
}