//Create your canvas
    private lazy var paintView: DrawingView = {
        $0.backgroundColor = .gray
        $0.uiDelegate = self
        $0.showToolPanel = false
        return $0
    }(DrawingView())
    
    override func viewDidLoad() {
        super.viewDidLoad()
    
        view.addSubview(paintView) //Add paintView to your view
    }
    
    //Delegate for init
    extension ViewController: DrawingViewDelegate {
        func presentViewController() -> UIViewController {
            return self
        }
    
        func rectForToolPanel() -> CGRect {
            return CGRect(x: 50, y: 150, width: 300, height: 100)
        }

    var rect = CGRect(x: 0, y: 0, width: 200, height: 200)
    paintView.setRect(rect: rect)

paintView.undo() 
paintView.redo()

paintView.clean()

paintView.save()