KitchenStories_buttonTitle.swift

enum LoginScreenState {
  case ShowLogIn
  case ShowSignUp
  
  var buttonTitle: String {
    switch self {
    case .ShowLogIn:
      return "Don't have an account?"
    case .ShowSignUp:
      return "Already have an account?"
    }
  }
  
  var cells: [AuthCellType] { ... }
}

class ViewController {

  override func viewDidLoad() {
    ...
    
    screenState.asObservable()
      .map { $0.buttonTitle }
      .bindTo(footerButton.rx_title(.Normal))
      .addDisposableTo(disposeBag)
      
    ...  
  }