更改TableHeaderView的高度

具体代码如下：

 [self.m_tableView beginUpdates];        CGRect newFrame = self.m_headView2.frame;        newFrame.size.height = newFrame.size.height -29;        self.m_headView2.frame = newFrame;        [self.m_tableView setTableHeaderView:self.m_headView2];        m_buyViewLayout.constant = -29;        [self.m_tableView endUpdates];