DrawingController

//
//  LoginViewController.swift
//  First screen
//
//  Created by karolis on 21/09/2019.
//  Copyright © 2019 karolis. All rights reserved.
//



import UIKit

class DrawingController: UIView {

    override func draw(_ rect: CGRect) {

        super.draw(rect)

        guard let context = UIGraphicsGetCurrentContext() else { return }


        context.setStrokeColor(UIColor.red.cgColor)
        context.setLineWidth(10)
        context.setLineCap(.butt)

        lines.forEach { (line) in
            for (i, p) in line.enumerated() {
                if i == 0 {
                    context.move(to: p)
                } else {
                    context.addLine(to: p)
                }
            }
        }

        context.strokePath()

    }


    var lines = [[CGPoint]]()

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        lines.append([CGPoint]())
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        guard let point = touches.first?.location(in: nil) else { return }

        guard var lastLine = lines.popLast() else { return }
        lastLine.append(point)
        lines.append(lastLine)

        setNeedsDisplay()
    }

}

class ViewController: UIViewController {

    let canvas = DrawingController()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(canvas)
        canvas.backgroundColor = .white
        canvas.frame = view.frame
    }

}