title: iOS CoreLocation checking CLLocation timestamp to use it
body: <p>How do you check a CLLocation object and decide whether you want to use it or discard the result and get a new location update instead?</p>
  
  <p>I saw the timestamp property on CLLocation, but I'm not sure how to compare that to the current time. </p>
  
  <p>Also, after I do compare the time and find the difference in seconds, what value should the difference be under for me to use that CLLocation object? What's a good threshold.</p>
  
  <p>Thanks!</p>