     var drawnFramesPerSecond: Double {
         var framesPerSecond = 0.0
         if let startDate = startDate {
-            let interval = NSDate().timeIntervalSince(startDate)
+            let interval = Date().timeIntervalSince(startDate)
             if interval > 0 {
                 framesPerSecond = Double(drawnFrameCount) / interval
             }

    }
    
    func tick(timer: Timer) {
        let elapsed = NSDate().timeIntervalSince(startDate!) - pausedTimeInterval
        let complete = elapsed / duration
        finished = cycles > 0.0 && complete > cycles
        if isPaused || finished || superview == nil {

                    if let _ = startDate,
                        let pausedDate = pausedDate
                    {
                        let morePausedTimeInterval = Date().timeIntervalSince(pausedDate)
                        pausedTimeInterval += morePausedTimeInterval
                    }
                    pausedDate = nil
