title: Swift stopwatch running slower than expected
body: <p>I am trying to implement a stopwatch into my app, but I've noticed that it actually runs slower than it should. Here is the code:</p>
  
  <pre><code>timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(display), userInfo: nil, repeats: true)
  
  func stringFromTimeInterval(interval: TimeInterval) -&gt; NSString {
      let ti = Int(interval)
      let minutes = ti / 6000
      let seconds = ti / 100
      let ms = ti % 100
      return NSString(format: "%0.2d:%0.2d.%0.2d",minutes,seconds,ms)
  }
  
  @objc func display() {
      interval += 1
      lapInterval += 1
      timeLabel.text = stringFromTimeInterval(interval: TimeInterval(interval)) as String
      lapLabel.text = stringFromTimeInterval(interval: TimeInterval(lapInterval)) as String
  }
  </code></pre>
  
  <p>Hopefully I've included enough information. Thanks in advance!</p>