presenter.swift

protocol Visualizer : class {
    func show(userName: String)
}

struct Router {
    let navigationController: UINavigationController
    
    func moveToAnotherScreen() {
        
    }
}

class Presenter {
    weak var visualizer: Visualizer? = nil
    
    let router: Router
    
    init(router: Router) {
        self.router = router
    }
    
    func start() {
        visualizer?.show(userName: "Siarhei Fedartsou")
    }
    
    func onUserAction() {
        router.moveToAnotherScreen()
    }
}