获取 ScrollerView 滚动结束(每次滚动结束只调用一次

// 滚动减速结束的时候调用（若无减速则不会调用）
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    [self reSubscribeValueChange];
}
// 拖动结束后将要开始减速时被调用
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    if(!decelerate){
        [self reSubscribeValueChange];
    }
}

@property (nonatomic,assign) float beforeScrollViewOffset;

- (void)reSubscribeValueChange{
    float currentOffset = self.scrollView.contentOffset.y;
    if (fabs(currentOffset-self.beforeScrollViewOffset) < 5) return;
    self.beforeScrollViewOffset = currentOffset;
    // 下面放置需要处理的代码
}