title: Calculate time difference in Cocoa
body: <p>I have got two timevalues in the format: %H%M%S  (E.G.161500)</p>
  
  <p>These values are text-based integers.</p>
  
  <p>Is there a simple function in Cocoa that calculates the difference between these two integers using a 60 seconds and minutes scale?</p>
  
  <p>So if</p>
  
  <pre><code>time 1 = 161500
  time 2 = 171500
  
  timedifference = 003000
  </code></pre>