Intento migrar delegado de DifficultyViewDelegate a observable. Este es mi DifficultyViewDelegate:

@objc protocol DifficultyViewDelegate: class {
  func levelDidIncrease()
  func levelDidDecrease()
}

Y mi vista de dificultad:

  weak var delegate: DifficultyViewDelegate?

  @IBAction func decreaseLevel(_ sender: Any) {
    delegate?.levelDidDecrease()
  }

  @IBAction func increaseLevel(_ sender: Any) {
    delegate?.levelDidIncrease()
  }

Y este es mi RxDifficultyViewDelegateProxy

class RxDifficultyViewDelegateProxy: DelegateProxy, DelegateProxyType {
  static func currentDelegateFor(_ object: AnyObject) -> AnyObject? {
    let difficultyView: DifficultyView = object as! DifficultyView
    return difficultyView.delegate
  }

  static func setCurrentDelegate(_ delegate: AnyObject?, toObject object: AnyObject) {
    let difficultyView: DifficultyView = object as! DifficultyView
    difficultyView.delegate = delegate as? DifficultyViewDelegate
  }
}

También agregué una extensión en mi DifficultyView:

extension DifficultyView {
  public var rx_delegate: RxDifficultyViewDelegateProxy {
    return  RxDifficultyViewDelegateProxy.proxyForObject(RxDifficultyViewDelegateProxy.self)
  }

  public var rx_levelDidIncrease: Observable<Void> {
    return rx_delegate.methodInvoked(#selector(DifficultyViewDelegate.levelDidIncrease)).map { _ in return }
  }
}

Pero parece que cuando lo hago:

difficultyView.rx_levelDidIncrease.asObservable().subscribe(onNext: {
  print("did increase")
}).addDisposableTo(disposeBag)

Nunca se llama. Alguien tiene algún puntero?