rxswift

1. vm data -> UI

viewModel.signingIn
  .bind(to: signingUpOulet.rx.isAnimating)
  .disposed(by: disposeBag)


viewModel.signupEnabled
            .subscribe(onNext: { [weak self] valid  in
                self?.signupOutlet.isEnabled = valid
                self?.signupOutlet.alpha = valid ? 1.0 : 0.5
            })
            .disposed(by: disposeBag)

// 自定义rx
viewModel.validatedUsername
            .bind(to: usernameValidationOutlet.rx.validationResult)
            .disposed(by: disposeBag)

extension Reactive where Base: UILabel {
    var validationResult: Binder<ValidationResult> {
        return Binder(base) { label, result in
            label.textColor = result.textColor
            label.text = result.description
        }
    }
}

// 手势
let tapBackground = UITapGestureRecognizer()
        tapBackground.rx.event
            .subscribe(onNext: { [weak self] _ in
                self?.view.endEditing(true)
            })
            .disposed(by: disposeBag)
        view.addGestureRecognizer(tapBackground)

// ui -》 vm 操作处理
usernameOutlet.rx.text.orEmpty.asObservable()
            .flatMapLatest { username in
                return validationService.validateUsername(username)
                    .observeOn(MainScheduler.instance)
                    .catchErrorJustReturn(.failed(message: "Error contacting server"))
            }
            .share(replay: 1)

2. observable 类型，可以被观察