title: AudioFileSetProperty returning 'kAudioFileUnsupportedPropertyError (pty?)'
body: <p>I'm having difficulties writing a audio file's metadata:</p>
  
  <pre><code>AudioFileID fileID = nil;
  AudioFileOpenURL((__bridge CFURLRef) url, kAudioFileReadWritePermission, 0, &amp;fileID );
  CFDictionaryRef piDict = nil;
  UInt32 piDataSize   = sizeof(piDict);   
  AudioFileGetProperty( fileID, kAudioFilePropertyInfoDictionary, &amp;piDataSize, &amp;piDict );
  NSLog(@"%@", (__bridge NSDictionary *)piDict);
  
  NSMutableDictionary *dict = (__bridge NSMutableDictionary*)piDict;
  [dict setObject:@"NEW ALBUM NAME" forKey:@"album"];
  piDict = (__bridge CFDictionaryRef)dict;
  piDataSize = sizeof(dict);
  OSStatus status = AudioFileSetProperty(fileID, kAudioFilePropertyInfoDictionary, piDataSize, &amp;piDict);
  </code></pre>
  
  <p>The NSLog on line #6 gives me a nice dictionary with ID3 information.
  But when I want to alter (for instance the album name, line  #9) I get an OSStatus 'pty?' in return.</p>
  
  <p>Anyone who can give me pointers on what I'm doing wrong.
  Or maybe even a better / simpler / quicker way to edit ID3 tags / metadata for audio files.</p>