(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSLog(@"%lf",scrollView.contentOffset.y);
NSInteger m = scrollView.contentOffset.y;
if ( m >= 0 )
{
UIView *view = (UIView *)[self.view viewWithTag:100];
view.backgroundColor = [UIColor colorWithRed:234/255.0 green:234/255.0 blue:234/255.0 alpha:0.5];
}
现在向下是可以了，但是向上的时候没有效果啊