Get the outline of a path

PathOutliningPath.swift

/// Given `path`, drawn with `width`, returns a new path outlining its edges
func pathOutliningPath(path:UIBezierPath, withWidth width:CGFloat, inSize size:CGSize) -> UIBezierPath
{
  UIGraphicsBeginImageContextWithOptions(size, false, 0)
  let ctx = UIGraphicsGetCurrentContext()
  CGContextSetLineWidth(ctx, width)
  CGContextAddPath(ctx, path.CGPath)
  CGContextReplacePathWithStrokedPath(ctx)
  let extractedCGPath = CGContextCopyPath(ctx)
  UIGraphicsEndImageContext()
  let extractedPath = UIBezierPath(CGPath: extractedCGPath!)
  return extractedPath
}