Extension for NSBezierPath and CGPath

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I was recently making a cross platform game, and ran into an issue where SKAction.follow expects an arch path to be of type CGPath. I quickly found an older extension and updated it to conform with Swift 3 and be universally compatible for cross platform (iOS and macOS) development. I hope it helps someone!

import AppKit

extension NSBezierPath

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

  /// Transforms the NSBezierPath into a CGPathRef
  /// :returns: The transformed NSBezierPath
  private func transformToCGPath() -> CGPath
    // Create path
    let path = CGMutablePath()
    let points = UnsafeMutablePointer<NSPoint>.allocate(capacity: 3)
    let numElements = self.elementCount
    let cgPoint1 = CGPoint(x: points[0].x, y: points[0].y)
    let cgPoint2 = CGPoint(x: points[1].x, y: points[1].y)
    let cgPoint3 = CGPoint(x: points[2].x, y: points[2].y)

    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: cgPoint1)
          case .lineToBezierPathElement :
            path.addLine(to: cgPoint1)
            didClosePath = false
          case .curveToBezierPathElement :
            path.addCurve(to: cgPoint1, control1: cgPoint2, control2: cgPoint3)
            didClosePath = false
          case .closePathBezierPathElement:
            didClosePath = true

      if !didClosePath { path.closeSubpath() }

    points.deallocate(capacity: 3)
    return path


Thanks to @juliensagot for the original extension!