iOS tableview滑动到底部自动加载，向上拽加载

- (void)scrollViewDidScroll:(UIScrollView *)aScrollView {
    CGPoint offset = aScrollView.contentOffset;
    CGRect bounds = aScrollView.bounds;
    CGSize size = aScrollView.contentSize;
    UIEdgeInsets inset = aScrollView.contentInset;
    float y = offset.y + bounds.size.height - inset.bottom;
    float h = size.height;
    // NSLog(@"offset: %f", offset.y);
    // NSLog(@"content.height: %f", size.height);
    // NSLog(@"bounds.height: %f", bounds.size.height);
    // NSLog(@"inset.top: %f", inset.top);
    // NSLog(@"inset.bottom: %f", inset.bottom);
    // NSLog(@"pos: %f of %f", y, h);

    float reload_distance = ;
    if(y > h + reload_distance) {
        NSLog(@"load more rows");
    }
}

向上拽

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
//    if (isLoading || !hasMore) return;
//    if(scrollView.contentSize.height - (scrollView.contentOffset.y + scrollView.bounds.size.height - scrollView.contentInset.bottom) <= 0 && scrollView.contentOffset.y > 0){
//        [self loadMore];
//    }
}