Notes

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var imageView: UIImageView!
@IBOutlet weak var toolIcon: UIButton!

var lastPoint = CGPoint.zero
var swiped = false

var red:CGFloat = 0.0
var green:CGFloat = 0.0
var blue:CGFloat = 0.0
var brushSize:CGFloat = 5.0
var opacityValue:CGFloat = 1.0

var tool:UIImageView!
var isDrawing = true
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
tool = UIImageView()
tool.frame = CGRect(x: self.view.bounds.size.width, y: self.view.bounds.height, width: 38, height: 38)
tool.image = #imageLiteral(resourceName: "brush")
self.view.addSubview(tool)
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
swiped = false
if let touch = touches.first{
lastPoint = touch.location(in: self.view)
}
}

func drawLines(fromPoint:CGPoint,toPoint:CGPoint){
UIGraphicsBeginImageContext(self.view.frame.size)
imageView.image?.draw(in: CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height))
let context = UIGraphicsGetCurrentContext()

context?.move(to: CGPoint(x: fromPoint.x, y: fromPoint.y))
context?.addLine(to: CGPoint(x: toPoint.x, y: toPoint.y))
tool.center = toPoint

context?.setBlendMode(CGBlendMode.normal)
context?.setLineCap(CGLineCap.round)
context?.setLineWidth(brushSize)
context?.setStrokeColor(UIColor(red: red, green: green, blue: blue, alpha:opacityValue).cgColor)
context?.strokePath()

imageView.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {

swiped = true
if let touch = touches.first{
let currentPoint = touch.location(in: self.view)
drawLines(fromPoint: lastPoint, toPoint: currentPoint)
lastPoint = currentPoint
}
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
if !swiped {
drawLines(fromPoint: lastPoint, toPoint: lastPoint)
}
}

@IBAction func reset(_ sender: AnyObject) {
self.imageView.image=nil
}

@IBAction func erase(_ sender: AnyObject) {
if(isDrawing){
(red, green, blue) = (1,1,1)
tool.image = #imageLiteral(resourceName: "eraser_icon")
toolIcon.setImage(#imageLiteral(resourceName: "brush"), for: .normal)
}else{
(red, green, blue) = (0,0,0)
tool.image = #imageLiteral(resourceName: "brush")
toolIcon.setImage(#imageLiteral(resourceName: "eraser_icon"), for: .normal)
}

isDrawing = !isDrawing
}

@IBAction func save(_ sender: AnyObject) {
if let image = imageView.image{
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)
}
}

@IBAction func setting(_ sender: AnyObject) {

}

@IBAction func colorChooser(_ sender: AnyObject) {

if sender.tag == 0{
(red, green, blue) = (0,0,0)
}else if sender.tag == 1{
(red, green, blue) = (1,0,0)
}else if sender.tag == 2{
(red, green, blue) = (0,1,0)
}else if sender.tag == 3{
(red, green, blue) = (0,0,1)
}else if sender.tag == 4{
(red, green, blue) = (1,1,0)
}else if sender.tag == 5{
(red, green, blue) = (0,1,1)
}

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

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
let settingsVC = segue.destination as! SettingVC
settingsVC.delegate = self
settingsVC.red = red
settingsVC.green = green
settingsVC.blue = blue
settingsVC.brushSize = brushSize
settingsVC.opacityValue = opacityValue
}


}

extension ViewController:UINavigationControllerDelegate, UIImagePickerControllerDelegate, SettingsVCDelegate{
func settingsViewControllerDidFinish(_ settingsVC: SettingVC) {
self.red = settingsVC.red
self.green = settingsVC.green
self.blue = settingsVC.blue
self.brushSize = settingsVC.brushSize
self.opacityValue = settingsVC.opacityValue
}
}