记录一段代码，判断scrollView向上滚动还是向下滚动

-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {

historyY = scrollView.contentOffset.y;

}

-(void)scrollViewDidScroll:(UIScrollView *)scrollView {

if (scrollView.contentOffset.y<historyY) {

NSLog(@"down");

else if (scrollView.contentOffset.y>historyY) {

NSLog(@"up");

}

}