RX.swift

override func didMoveToSuperview() {
    super.didMoveToSuperview()
    addObserver(.contentOffset)
    addObserver(.panGesture)
}

//MARK: - observers
/// Add scroll view content y offset and scroll view panGesture observers
/// - Parameter observer: RefreshControl.Observer type
private func addObserver(_ observer : Observer){
    guard let scrollView = containerScrollView else {return}

    switch observer {
    case .contentOffset:
        scrollView.rx.contentOffset.bind(onNext: {[weak self] offset in
            self?.scrollViewContentYOffset = -offset.y
            self?.setNeedsDisplay()
            }).disposed(by: bag)
        break

    case .panGesture:
        scrollView.panGestureRecognizer.rx.event.bind(onNext: {[weak self] panGesture in
            self?.xPositionOfPan = panGesture.location(in: self?.containerScrollView).x
            self?.setNeedsDisplay()

            switch panGesture.state{
            case .cancelled,.failed,.ended:
                if (self?.scrollViewContentYOffset)! > (self?.thresholdDrag)!{
                    self?.refreshingStatus = true
                    self?.setNeedsDisplay()
                    self?.animateRefreshCircle()
                    self?.onRefreshing()
                }
                break
            default:
                break
            }
            }).disposed(by: bag)
        break
    }
}