title: how append nsdata
body: <p>how i could append nsdata, i would append lenght data on first message to send on socket
  i use code like this but error on runing.</p>
  
  <pre><code>int lendata = [message length];
  NSData *firstdata = [NSData dataWithBytes: &amp;lendata length: sizeof(lendata)];
  NSData *mdata = [message dataUsingEncoding:NSUTF8StringEncoding];
  NSMutableData *seconddata = [NSData dataWithData:mdata];
  [firstdata appendData:secondata];
  </code></pre>
  
  <p>please tell if there is another way
  Thanks for your help.</p>