#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat sectionHeaderHeight = tableHeaderHeight;
    if (scrollView == self.table) {
        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);
        }
    }
}

參考鏈接：
Change Default Scrolling Behavior of UITableView Section Header