title: Unique identifier for an iPhone app
body: <p>For an iPhone app that submits images to a server I need somehow to tie all the images from a particular phone together.  With every submit I'd like to send some unique phone id.  Looked at <pre>
    [[UIDevice mainDevice] uniqueIdentifier]<br>
  and
    [[NSUserDefaults standardDefaults] stringForKey:@"SBFormattedPhoneNumber"]
  </pre></p>
  
  <p>but getting errors in the simulator.</p>
  
  <p>Is there an Apple sanctioned way of doing this?</p>