如何调整UITableView的大小以自定义动态扩展UITableViewCell

I'm using a custom UITableViewCell I've created to expand a cell when it's touched. I do this using beginUpdates/endUpdates, which in turn call heightForRowAtIndexPath. It works fine, the cell expands, the label I have on it displays. All good so far.I'm using a custom UITableViewCell I've created