如何使用RestKit映射XML textContent？

I have a XML like this:

我有这样的XML:

<rss>
<channel>
 <item>
  <title>something</title>
  <description>...</description>
  <category>cooking</category>
  <category>housing</category>
 </item>

 <item>
  ...
 </item>
 ...
</channel>
</rss>
<rss>
<ch