CoordinatorAddition.swift

import UIKit

extension ViewController {
    @IBAction func blueTapped(_ sender: Any) {
        coordinator?.goToBlueView()
    }
}

extension MainCoordinator {
    
    func goToBlueView() {
        let vc = BlueViewController.instantiate()
        vc.coordinator = self
        navigationController.pushViewController(vc, animated: true)
    }
}

class BlueViewController: UIViewController, Storyboarded {
    weak var coordinator: Coordinator?
}