화면 탭했을 때 키보드 내려가게 하기

func setupBinding() {
    let tapper = UITapGestureRecognizer()

    tapper.rx.event.asDriver()
        .drive(onNext: { [weak self] _ in
            self?.view.endEditing(true)
        })
        .disposed(by: disposeBag)
    view.addGestureRecognizer(tapper)
}