title: ios7 UITableView Height , changed but return to default
body: <p>i'm newer.
  i find a strange problem about UITableview.</p>
  
  <p>when the uitableview be loaded, the height is 400.
  and then ,in program, i change the uitableview's height</p>
  
  <pre><code>CGRect talkListFrame = _talkList.frame;
  talkListFrame.size.height = _talkListOriginalHeight -keyboardSize.height;
  [_talkList setFrame:talkListFrame];
  </code></pre>
  
  <p>it was good, i changed the height of the uitableview(talkList).
  but ,when i put data to the uitableview, the height of uitableview return to 400.
  ※i used a custom uitableviewcell, just put a label in the cell.</p>
  
  <pre><code>UILabel *lable = (UILabel*)[cell viewWithTag:6];
  lable.text =@"xxxx";
  </code></pre>
  
  <p>if i do not use a custom uitablecell, it was good,the height not return.</p>
  
  <pre><code>cell.textLabel.text =@"";
  </code></pre>
  
  <p>why? the custom cell is the problem</p>