title: Why the UIButton in UITableViewCell.contentView won't work?
body: <p>I've did lots of tests and searches and still couldn't find why the <code>UIButton</code> that I added into a <code>UITableViewCell.contentView</code> won't work. I can guarantee I did everything right, the button still won't answer the <code>TouchUpInside</code> event.</p>
  
  <p>code like this won't work:</p>
  
  <pre><code>[self.contentView addSubview:theButton];
  </code></pre>
  
  <p>But this would work:</p>
  
  <pre><code>[self addSubview:theButton];
  </code></pre>
  
  <p>As you may expected, <code>self</code> was a subclass of <code>UITableViewCell</code>. and recording to the doc, shouldn't we always add things to <code>contentView</code>?</p>
  
  <p>Sorry for my poor English. I hope I described it clearly.</p>