DITranquillity

.package(url: "https://github.com/ivlevAstef/DITranquillity.git", from: "4.6.0")

.product(name: "DITranquillity")

.................................................
/// Dependency description

let container = DIContainer()

container.register(LoginRouter.init)

container.register(LoginPresenterImpl.init)
  .as(LoginPresenter.self)
  .lifetime(.objectGraph)

container.register(LoginViewController.init)
  .injection(cycle: true, \.presenter)
  .as(LoginView.self)
  .lifetime(.objectGraph)

container.register(AuthInteractorImpl.init)
  .as(AuthInteractor.self)

.................................................
/// Application start point

let router: LoginRouter = container.resolve()
window.rootViewController = router.rootViewController
router.start()

.................................................
/// Application Code

import SwiftLazy

class LoginRouter {
    let rootViewController = UINavigationController()
    private let loginPresenterProvider: Provider<LoginPresenter>
    
    init(loginPresenterProvider: Provider<LoginPresenter>) {
        loginPresenterProvider = loginPresenterProvider
    }
    
    func start() {
        let presenter = loginPresenterProvider.value
        presenter.loginSuccessCallback = { [weak self] _ in
            ...
        }
        // Your can write code without force cast, it's code simple example
        rootViewController.push(presenter.view as! UIViewController)
    }
}

protocol LoginPresenter: class {
    var loginSuccessCallback: ((_ userId: String) -> Void)?
    func login(name: String, password: String)
}

protocol LoginView: class {
    func showError(text: String)
}

class LoginPresenterImpl: LoginPresenter {
    private weak var view: LoginView?
    private let authInteractor: AuthInteractor
    init(view: LoginView, authInteractor: AuthInteractor) {
        self.view = view
        self.authInteractor = authInteractor
    }
    
    func login(name: String, password: String) {
        if name.isEmpty || password.isEmpty {
            view?.showError(text: "fill input")
            return
        }
        
        authInteractor.login(name: name, password: password, completion: { [weak self] result in
            switch result {
            case .failure(let error): 
                self?.view?.showError(text: "\(error)")
            case .success(let userId):
                self?.loginSuccessCallback?(userId)
            }
        })
    }
}

class LoginViewController: UIViewController, LoginView {
    var presenter: LoginPresenter!
    ...
    func showError(text: String) {
        showAlert(title: "Error", message: text)
    }
    
    private func tapOnLoginButton() {
        presenter.login(name: nameTextField.text ?? "", password: passwordTextField.text ?? "")
    }
}

protocol AuthInteractor: class {
    func login(name: String, password: String, completion: (Result<String, Error>) -> Void)
}

class AuthInteractorImpl: AuthInteractor {
    func login(name: String, password: String, completion: (Result<String, Error>) -> Void) {
        ...
    }
}