title: How to find an audio file's length (in seconds)
body: <p>(Objective C) 
  Just using simple AudioServicesPlaySystemSoundID and its counterparts, but I can't find in the documentation if there is already a way to find the length of an audio file.</p>
  
  <p>I know there is AudioServicesGetPropertyInfo, but that seems to return a byte-buffer - do audio files embed their length in themselves and I can just extract it with this?</p>
  
  <p>Or is there perhaps a formula based on bit-rate * fileSize to convert to length-of-time?</p>
  
  <p>mIL3S</p>
  
  <p>www.milkdrinkingcow.com</p>