How to draw a line in Swift 3

Question

I would like the user to touch 2 points and then a line is drawn between those two points. Here is what I have so far:

func drawline(){
    let context = UIG         


        

Answer 1

Draw line in Swift 4.1

class MyViewController: UIViewController {

    @IBOutlet weak var imgViewDraw: UIImageView!

    var lastPoint = CGPoint.zero
    var red: CGFloat = 0.0
    var green: CGFloat = 0.0
    var blue: CGFloat = 0.0
    var brushWidth: CGFloat = 10.0
    var opacity: CGFloat = 1.0
    var isSwiping:Bool!


    override func viewDidLoad() {
        super.viewDidLoad()


    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    //MARK: Touch events
    override func touchesBegan(_ touches: Set, with event: UIEvent?) {
        isSwiping    = false
        if let touch = touches.first{
            lastPoint = touch.location(in: imgViewDraw)
        }
    }
    override func touchesMoved(_ touches: Set, with event: UIEvent?) {

        isSwiping = true;
        if let touch = touches.first{
            let currentPoint = touch.location(in: imgViewDraw)
            UIGraphicsBeginImageContext(self.imgViewDraw.frame.size)
            self.imgViewDraw.image?.draw(in: CGRect(x:0, y:0,width:self.imgViewDraw.frame.size.width, height:self.imgViewDraw.frame.size.height))

            UIGraphicsGetCurrentContext()?.move(to: CGPoint(x: lastPoint.x, y: lastPoint.y))
            UIGraphicsGetCurrentContext()?.addLine(to: CGPoint(x: currentPoint.x, y: currentPoint.y))

            UIGraphicsGetCurrentContext()?.setLineCap(CGLineCap.round)
            UIGraphicsGetCurrentContext()?.setLineWidth(self.brushWidth)
            UIGraphicsGetCurrentContext()?.setStrokeColor(red: red, green: green, blue: blue, alpha: 1.0)
            UIGraphicsGetCurrentContext()?.strokePath()


            self.imgViewDraw.image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            lastPoint = currentPoint
        }
    }
    override func touchesEnded(_ touches: Set, with event: UIEvent?) {
        if(!isSwiping) {
            // This is a single touch, draw a point
            UIGraphicsBeginImageContext(self.imgViewDraw.frame.size)
            self.imgViewDraw.image?.draw(in: CGRect(x:0, y:0,width:self.imgViewDraw.frame.size.width, height:self.imgViewDraw.frame.size.height))
            UIGraphicsGetCurrentContext()?.setLineCap(CGLineCap.round)
            UIGraphicsGetCurrentContext()?.setLineWidth(self.brushWidth)

            UIGraphicsGetCurrentContext()?.move(to: CGPoint(x: lastPoint.x, y: lastPoint.y))
            UIGraphicsGetCurrentContext()?.addLine(to: CGPoint(x: lastPoint.x, y: lastPoint.y))
            UIGraphicsGetCurrentContext()?.setStrokeColor(red: red, green: green, blue: blue, alpha: 1.0)
            UIGraphicsGetCurrentContext()?.strokePath()
            self.imgViewDraw.image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
        }
    }


}