Ended up doing it this way:
func drawLineFromPoint(start : CGPoint, toPoint end:CGPoint, ofColor lineColor: UIColor, inView view:UIView) {
//design the path
let path = UIBezierPath()
path.move(to: start)
path.addLine(to: end)
//design path in layer
let shapeLayer = CAShapeLayer()
shapeLayer.path = path.cgPath
shapeLayer.strokeColor = lineColor.CGColor
shapeLayer.lineWidth = 1.0
view.layer.addSublayer(shapeLayer)
}