title: How to return CFDataRef without memory leak?[ios]
body: <p>When I return a <code>CFDataRef</code> by </p>
  
  <pre><code>(CFDataRef)MyFunction{
      .....
      CFDataRef data = CFDataCreate(NULL, buf, bufLen);
      free(buf);
      return data;
  }
  </code></pre>
  
  <p>There is a memory leak, how to make <code>CFDataRef</code> autorelease?
  the method [data autorelease] doesn't exit.</p>