设置headview跟随滚动

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

CGFloat sectionHeaderHeight = 40;

if (scrollView.contentOffset.y<=sectionHeaderHeight&&scrollView.contentOffset.y>=0) {

    

    scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);

} else if (scrollView.contentOffset.y>=sectionHeaderHeight) {

    

    scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);

}

}