colouring NSImage

ViewController.swift

//
//  ViewController.swift
//  NSImageColoring
//
//  Created by ing.conti on 21/03/2019.
//  Copyright © 2019 ing.conti. All rights reserved.
//

import Cocoa

class ViewController: NSViewController {

    @IBOutlet weak var original: NSImageView!
    @IBOutlet weak var tinted: NSImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        
        let img = NSImage(named: "stackoverflow")
        let tintedImg = img?.tint(with: NSColor.white)


        self.original.image = img
        self.tinted.image = tintedImg
    }

    override var representedObject: Any? {
        didSet {
        // Update the view, if already loaded.
        }
    }


}




extension NSImage {
    
    func tint(with color: NSColor) -> NSImage {
        // make a copy, otherwise change the same image (i.e. self)
        // for efficiency You can also use "self" directly replacing "copy" with "self".
        let copy = self.copy() as! NSImage
        copy.lockFocus()
        color.set()
        let srcSpacePortionRect = NSRect(origin: CGPoint(), size: self.size)
        srcSpacePortionRect.fill(using: .sourceAtop)
        copy.unlockFocus()
        return copy
    }
}