Round specified corners of UIView

UIView+round.swift

// Example: view.round([.TopLeft, .TopRight], radius: 15)

extension UIView {
	/**
	Rounds the given set of corners to the specified radius
	
	- parameter corners: Corners to round
	- parameter radius:  Radius to round to
	*/
	func round(corners: UIRectCorner, radius: CGFloat) {
		_round(corners, radius: radius)
	}
	
	/**
	Rounds the given set of corners to the specified radius with a border
	
	- parameter corners:     Corners to round
	- parameter radius:      Radius to round to
	- parameter borderColor: The border color
	- parameter borderWidth: The border width
	*/
	func round(corners: UIRectCorner, radius: CGFloat, borderColor: UIColor, borderWidth: CGFloat) {
		let mask = _round(corners, radius: radius)
		addBorder(mask, borderColor: borderColor, borderWidth: borderWidth)
	}
	
	/**
	Fully rounds an autolayout view (e.g. one with no known frame) with the given diameter and border
	
	- parameter diameter:    The view's diameter
	- parameter borderColor: The border color
	- parameter borderWidth: The border width
	*/
	func fullyRound(diameter: CGFloat, borderColor: UIColor, borderWidth: CGFloat) {
		layer.masksToBounds = true
		layer.cornerRadius = diameter / 2
		layer.borderWidth = borderWidth
		layer.borderColor = borderColor.CGColor;
	}
	
	
	private func _round(corners: UIRectCorner, radius: CGFloat) -> CAShapeLayer {
		let path = UIBezierPath(roundedRect: bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
		let mask = CAShapeLayer()
		mask.path = path.CGPath
		self.layer.mask = mask
		return mask
	}
	
	private func addBorder(mask: CAShapeLayer, borderColor: UIColor, borderWidth: CGFloat) {
		let borderLayer = CAShapeLayer()
		borderLayer.path = mask.path
		borderLayer.fillColor = UIColor.clearColor().CGColor
		borderLayer.strokeColor = borderColor.CGColor
		borderLayer.lineWidth = borderWidth
		borderLayer.frame = bounds
		layer.addSublayer(borderLayer)
	}
}