view.swift

// command
plusBtn.tap
  .map(ViewModel.Command.plus)
  .bind(to: viewModel.command)
  .disposed(by: disposeBag)

minusBtn.tap
  .map(ViewModel.Command.minus)
  .bind(to: viewModel.command)
  .disposed(by: disposeBag)


// state
viewModel.state
  .numValue
  .drive(label.rx.text)
  .disposed(by: disposeBag)

viewmodel.swift

  enum Command {
    case plus
    case minus
  }
  
  // MARK: Action
  
  struct Action {
    let numValue: Variable<Int> = Variable(0)
  }
  
  // MARK: State
  
  struct State {
    let numValue: Driver<Int>
    
    init(action: Action) {
      numValue = action.numValue.asDriver()
    }
  }
  
  // MARK: Properties
  
  var disposeBag = DisposeBag()
  var command: PublishSubject<Command>
  var action: Action
  var state: State
  
  init() {
    command = PublishSubject()
    action = Action()
    state = State(action: action)

    commandBind()
  }
  
  func commandBind() {
    command.asObservable()
      .subscribe(onNext: { [weak self] command in                          
        switch command {
        case .plus:
          self?.action.numValue.value = self?.action.numValue.value + 1
          
        case .minus:
          self?.action.numValue.value = self?.action.numValue.value - 1
          
        default:
          break
        }
      })
      .disposed(by: self.disposeBag)
  }