title: timestamp and subtract objective C
body: <p>I need to find the specific time a tap happens and then the time since it has passed.  I have the app counting taps, I just haven't figured out the time thing.</p>
  
  <p>I tried:</p>
  
  <pre><code>timeStamp = [[NSDate date] timeIntervalSince1970]; 
  </code></pre>
  
  <p>but I'm new to obj c and clearly there is a syntax problem.</p>
  
  <p>Thanks for anyhelp.</p>