title: CLLocation speed
body: <p>I am developing GPS application.
  Do you know about how to detect speed of mobile device ?</p>
  
  <p>Actually, I need to detect the speed every 2 seconds.</p>
  
  <p>I know <strong><code>didUpdateToLocation</code></strong> method is called when location changed.</p>
  
  <pre><code>- (void)locationManager:(CLLocationManager *)manager
      didUpdateToLocation:(CLLocation *)newLocation
             fromLocation:(CLLocation *)oldLocation
  </code></pre>
  
  <p>But I think this method is not suitable for my issue. </p>
  
  <p>So, Do I need to check speed of <code>[CLLocationManager location]</code> in 2 seconds ?</p>
  
  <p>Any suggestion ?</p>
  
  <p>Thanks in advance.</p>