여러 스크롤 뷰가 겹쳐 있을 때 제스쳐 뒤로 넘기기

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {

        if (gestureRecognizer is UIPanGestureRecognizer || gestureRecognizer is UIRotationGestureRecognizer) {

            return true

        } else {

            return false

        }

    }

: UIScrollView, UIGestureRecognizerDelegate