gistfile1.swift

NSAnimationContext.runAnimationGroup({ (context) -> Void in
            
            var transition:CATransition = CATransition()
            transition.duration = 0.3
            transition.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
            transition.type = kCATransitionPush
            transition.subtype = kCATransitionFromRight
            transition.delegate = self
            context.duration = 0.5
            topVC.view.animator().alphaValue = 1
            bottomVC.view.animator().alphaValue = 0
            
            topVC.view.frame = ????

        }, completionHandler: nil)