Should I use a PublishSubject if I am notifying an action is complete?

I am learning Viper w/ RxSwift.

I would like to notify my Presenter that viewDidLoad was called in my ViewController.

To do this I have the following:

class LoginPresenter {

    weak var view: LoginView?
    var interactor: LoginUseCase?
    var router: LoginRouter?

    private(set) var viewDidLoad = PublishSubject<Void>()

    private lazy var disposeBag = DisposeBag()

    required init(view: LoginView?, interactor: LoginUseCase?, router: LoginRouter?) {
        self.view = view
        self.interactor = interactor
        self.router = router

        viewDidLoad
            .subscribe(onNext: { _ in
                // do something on viewDidLoad
            }).disposed(by: disposeBag)
    }
}

class LoginViewController: UIViewController {

    var presenter: LoginPresenter?

    override func viewDidLoad() {
        super.viewDidLoad()

        presenter?.viewDidLoad.onNext(())
    }
}

Once my view is loaded I am calling presenter?.viewDidLoad.onNext(())

I am then able to trigger any actions within my presenter, such as calling out to my router to ensure navigation is configured or my interactor.

Should I be using a PublishSubject for this? Or does RxSwift have a better suited type?

I feel like this approach means I will end up with something like

        viewDidLoad
            .subscribe(onNext: { _ in
                self.router?.viewDidLoad.onNext(())
            }).disposed(by: disposeBag)

Hmm... A Presenter's job is to gather up user actions and I'm not so sure we should consider viewDidLoad a user action. And in any case, the Wireframe (which handles routing) shouldn't need to know when viewDidLoad is called in the first place; its job is to present new screens and you can't present a screen in viewDidLoad.

That said, you can setup your connection in the ViewController's presenter didSet:

final class ViewController: UIViewController {

    var presenter: Presenter? {
        didSet {
            guard let presenter = presenter else { viewDidLoadDisposable.dispose(); return }
            viewDidLoadDisposable.disposable = rx.methodInvoked(#selector(viewDidLoad))
                .map { _ in }
                .bind(to: presenter.viewDidLoad)
        }
    }

    let viewDidLoadDisposable = SerialDisposable()

    deinit {
        viewDidLoadDisposable.dispose()
    }
}

final class Presenter {
    let viewDidLoad = PublishSubject<Void>()
}

In general though, it is in the viewDidLoad where the presenter and viewController elements are normally bound together so the above code has a pretty unnatural feel.

Also, Observables, Subjects and the DisposeBag should not be vars, use lets instead. That's the "functional" part of functional reactive programming.