Swift - Using CGContext to draw with finger

Question

I\'m trying to make a drawing app. I have a single custom UIView:

class DrawView: UIView {

var touch : UITouch!
var lastPoint : CGPoint!
var currentPoint : CGPo         


        

Answer 1

marcomoreira92 and Keuha's version worked for me, but I don't like to use indices that much. Thus here is an alternative version, which was tested in Swift 4.2:

class DrawView: UIView {

    var lineArray: [[CGPoint]] = [[CGPoint]]()

    override func touchesBegan(_ touches: Set, with event: UIEvent?) {
        guard let touch = touches.first else { return }
        let firstPoint = touch.location(in: self)
        lineArray.append([CGPoint]())
        lineArray[lineArray.count - 1].append(firstPoint)
    }

    override func touchesMoved(_ touches: Set, with event: UIEvent?) {
        guard let touch = touches.first else { return }
        let currentPoint = touch.location(in: self)
        lineArray[lineArray.count - 1].append(currentPoint)
        setNeedsDisplay()
    }

    override func draw(_ rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()
        context?.setLineWidth(5)
        context?.setStrokeColor(UIColor.black.cgColor)
        context?.setLineCap(.round)

        for line in lineArray {
            guard let firstPoint = line.first else { continue }
            context?.beginPath()
            context?.move(to: firstPoint)
            for point in line.dropFirst() {
                context?.addLine(to: point)
            }
            context?.strokePath()
        }
    }
}