scrollview滑动到某区域执行某种方法

-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGPoint offset = scrollView.contentOffset;//scrollview当前显示区域定点相对于fram顶点的偏移量
    CGRect bounds = scrollView.bounds;//原点
    CGSize size = scrollView.contentSize;//scrollview可以滚动的区域
    UIEdgeInsets inset = scrollView.contentInset;//scrollview的contentview的顶点相对于scrollview的位置
    CGFloat currentOffset = offset.y + bounds.size.height - inset.bottom;
    CGFloat maximumOffset = size.height;
    //currentOffset与maximumOffset的值相等时，说明scrollview已经滑到底部了，即偏移量达到最大值
    if (offset.y <= 0) {
        DLog(@"滑到顶部");
        SCV.contentOffset = CGPointMake(0, 0);
        return;
    }
    if (currentOffset >= maximumOffset) {
        DLog(@"滑到底部");
        //        scrollView.contentOffset = CGPointMake(0, bounds.size.height - offset.y);
        //        return;
    }
}