swift | 控制UIScrollView实现滑动分页效果

这里以横向滑动为例，竖向同理，过程可以参考注释。

var dataList:[Any] = [] //数据源
var lastContentOffset: CGFloat = 0 //上次滑动的偏移量
var isDrag:Bool = false//是否处于滑动状态

//MARK: - UIScrollViewDelegate
extension ZJJTBaseVC: UIScrollViewDelegate {
    
    //开始拖拽
    func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
        //记录偏移量
        lastContentOffset = scrollView.contentOffset.x
        //业务逻辑
        if dataList.count > 0 {
            isDrag = true
        }
    }
    
    //结束拖拽
    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if decelerate == false {//没有减速
            scrollViewHandleScrollWithScrollView(scrollView)
            //业务逻辑
            if dataList.count > 0 {
                DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 3) {
                    self.isDrag = false
                }
            }
        }
    }
    
    //开始减速
    func scrollViewWillBeginDecelerating(_ scrollView: UIScrollView) {
        //开始减速（即手指离开屏幕）立即停止滚动
        scrollView.setContentOffset(scrollView.contentOffset, animated: false)
        scrollViewHandleScrollWithScrollView(scrollView)
        //业务逻辑
        if dataList.count > 0 {
            DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 3) {
                self.isDrag = false
            }
        }
    }
    
    //处理滑动到哪一个cell
    func scrollViewHandleScrollWithScrollView(_ sender: UIScrollView) {
        let offset = sender.contentOffset.x
        if offset > lastContentOffset && offset - lastContentOffset > 30 {//右滑
            if scrollIndex != dataList.count - 1 {
                scrollIndex += 1
            }
        } else if offset < lastContentOffset && lastContentOffset - offset > 30 {//左滑
            if scrollIndex != 0 {
                scrollIndex -= 1
            }
        }

        //业务逻辑
        if collectionView != nil {
            collectionView.scrollToItem(at: IndexPath.init(item: scrollIndex, section: 0), at: .centeredHorizontally, animated: true)
            if scrollIndex == currentIndex {
                let cell = self.collectionView.cellForItem(at: IndexPath.init(item: self.currentIndex, section: 0)) as? ZJJTBaseCollectionCell
                if cell != nil {
                    cell!.isPlay = isPlay
                }
            }
        }
    }
}