https://medium.com/@aronbalog/2-ios-reinventing-view-controller-navigation-6d3499d4df73

ColorViewController.swift

import UIKit
import CoreNavigation
import ChromaColorPicker

class ColorViewController: UIViewController {
    lazy var colorPicker: ChromaColorPicker = {
        let view = ChromaColorPicker(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
        view.padding = 5
        view.stroke = 3
        view.hexLabel.textColor = UIColor.black
        view.delegate = self
        
        return view
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.addSubview(colorPicker)
        
        colorPicker.center = view.center
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        colorPicker.adjustToColor(view.backgroundColor ?? .black)
    }
}