title: Append NSData to a file in Objective C
body: <p>I'm attempting to download a large file on the iPhone and save it to disk as it is downloaded.</p>
  
  <p>Ideally, in:</p>
  
  <pre><code>-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data {
  
  }
  </code></pre>
  
  <p>I want to append 'data' to a file on disk.</p>
  
  <p>I've checked out the NSData documentation. There are functions to write to a file, but I can't see anything to append to an existing file. </p>
  
  <p>Does anyone know how I can append this data? Any help much appreciated!
  Nick.</p>