UIViewControllerAnimatedTransitioning? { let animationController = PhotoSlider.ZoomingAnimationController(present: false) animationController.sourceTransition = dismissed as? ZoomingAnimationControllerTransitioning animationController.destinationTransition = self return animationController } func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? { let animationController = PhotoSlider.ZoomingAnimationController(present: true) animationController.sourceTransition = source as? ZoomingAnimationControllerTransitioning animationController.destinationTransition = presented as? ZoomingAnimationControllerTransitioning return animationController }