btn = TKTransitionSubmitButton(frame: CGRectMake(0, 0, 44, 44))

func didStartYourLoading() {
    btn.startLoadingAnimation()
}

func didFinishYourLoading() {
    btn.startFinishAnimation {
        //Your Transition
        let secondVC = SecondViewController()
        secondVC.transitioningDelegate = self
        self.presentViewController(secondVC, animated: true, completion: nil)
    }
}

// MARK: UIViewControllerTransitioningDelegate
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    let fadeInAnimator = TKFadeInAnimator()
    return fadeInAnimator
}
func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return nil
}