ViewControllerSeparated.swift

import UIKit

class ViewController: UIViewController {
    
    lazy var blueView: ViewControllerView = {
        let view = ViewControllerView(viewColor: .systemBlue, target: self, selector: #selector(presentAlert))
        return view
    }()
    
    override func loadView() {
        view = blueView
    }
    
    @objc private func presentAlert() {
        let alertController = UIAlertController(title: "Hello", message: "World", preferredStyle: .alert)
        let action = UIAlertAction(title: "Ok", style: .default)
        alertController.addAction(action)
        present(alertController, animated: true)
    }

}