Convert NSBezierPath to CGPath (Swift 4, Xcode 9.2)

## NSBezierPath+cgPath.swift
extension NSBezierPath {

	var cgPath: CGPath {
		get { return self.transformToCGPath() }
	}

	/// Transforms the NSBezierPath into a CGPath
	///
	/// :returns: The transformed NSBezierPath
	private func transformToCGPath() -> CGPath {

		// Create path
		var path = CGMutablePath()
		var points = UnsafeMutablePointer<NSPoint>.allocate(capacity: 3)
		let numElements = self.elementCount

		if numElements > 0 {

			var didClosePath = true

			for index in 0..<numElements {

				let pathType = self.element(at: index, associatedPoints: points)

				switch pathType {

				case .moveToBezierPathElement:
					path.move(to: CGPoint(x: points[0].x, y: points[0].y))
				case .lineToBezierPathElement:
					path.addLine(to: CGPoint(x: points[0].x, y: points[0].y))
					didClosePath = false
				case .curveToBezierPathElement:
					path.addCurve(to: CGPoint(x: points[0].x, y: points[0].y), control1: CGPoint(x: points[1].x, y: points[1].y), control2: CGPoint(x: points[2].x, y: points[2].y))
					didClosePath = false
				case .closePathBezierPathElement:
					path.closeSubpath()
					didClosePath = true
				}
			}

			if !didClosePath { path.closeSubpath() }
		}

		points.deallocate(capacity: 3)
		return path
	}
}