title: Application expiration using NSTimeInterval
body: <p>How would I set this method to display the alert panel 30 days from the initial launch of the application?</p>
  
  <pre><code>-(void)awakeFromNib
  
  {
  
      NSDate * today = [NSDate date];
  
      NSTimeInterval expiry = ();
  
  
      if ([today timeIntervalSinceReferenceDate] &gt; expiry){
          NSRunAlertPanel(@"Trial period has ended", @"Please Register", nil, nil, nil);
          NSLog(@"expired");
          [[NSApplication sharedApplication] terminate:self];
      }
  
  }
  </code></pre>