title: NSTimer Accuracy
body: <p>I am currently working on an app that requires a sound file to be played at exact intervals, which are variable in duration.</p>
  
  <p>I seem to remember being told that NSTimer simply places an operation onto the stack after the specified duration, rather than the operation being run after the specified duration. This would mean that if there were lots of other operations on the stack before it, it would not be called on time. </p>
  
  <p>I would like to know if this is indeed correct, and if so, is there any way of getting an operation to be guaranteed to run after a specified duration.</p>
  
  <p><em>Before any makes the comment that the sound files may be delayed the first time, they are already pre-loaded to avoid this.</em></p>