title: Get current NSDate in timestamp format
body: <p>I have a basic method which gets the current time and sets it in a string. However, how can I get it to format the current date &amp; time in a UNIX since-1970 timestamp format?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>NSDate *currentTime = [NSDate date];
  NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
  [dateFormatter setDateFormat:@"hh-mm"];
  NSString *resultString = [dateFormatter stringFromDate: currentTime];
  </code></pre>
  
  <p>Is it possible to use <code>NSDateFormatter</code> to change the 'resultString' into a timestamp?</p>