title: NSTimer: floating point value can not be converted to UInt8 because it is greater than UInt8.max
body: <p>My code returns the error: fatal error: floating point value can not be converted to UInt8 because it is greater than UInt8.max. The code is being called when a button is pressed (in a different swift file) but I know that the problem wasn't with calling the function so I didn't include it.</p>
  
  <p>code:</p>
  
  <pre><code>//starts the timer
  func startTimer(sender: AnyObject)
  {
  if !timer.valid
  {
      timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: sender, selector:     Selector(updateTime()), userInfo: nil, repeats: true)
      startTime = NSDate.timeIntervalSinceReferenceDate()
      //disp = timerDisplay
  }
  }
  
  //function that configures the timer
  func updateTime()
  {
  var currentTime = NSDate.timeIntervalSinceReferenceDate()
  
  //find the difference between the current time and the start time
  var elapsedTime: NSTimeInterval = currentTime - startTime
  
  //calculate the seconds in elapsed time
  let seconds = UInt8(elapsedTime)
  elapsedTime -= NSTimeInterval(seconds)
  
  ///find out the fraction of milliseconds to be displayed
  let fraction = UInt8(elapsedTime * 10)
  
  //add the leading zero for minutes, seconds and millseconds and store them as string constants
  //let strMinutes = minutes &gt; 9 ? String(minutes):"0" + String(minutes)
  let strSeconds = seconds &gt; 9 ? String(seconds):"0" + String(seconds)
  let strFraction = fraction &gt; 9 ? String(fraction):"0" + String(fraction)
  
  //display the time left to a string
  timerDisplay = "\(strSeconds):\(strFraction)"
  }
  
  func stopTimer()
  {
  timer.invalidate()
  }
  </code></pre>