MenuTransition.swift

enum TransitionState {
    case present
    case dismiss
}

class MenuTransition: NSObject, UIViewControllerAnimatedTransitioning {
    private var state: TransitionState = .present
    let interactor = Interactor()
    
    func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
        let presentationController = PresentationController(presentedViewController: presented, presenting: presenting)
        presentationController.interactor = interactor
        return presentationController
    }
    
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.3
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let container = transitionContext.containerView
        let duration = transitionDuration(using: transitionContext)
        switch state {
        case .present:
            present(duration: duration, container: container, transitionContext: transitionContext)
        case .dismiss:
            dismiss(duration: duration, container: container, transitionContext: transitionContext)
        }
    }
    
    private func present(duration: TimeInterval, container: UIView, transitionContext: UIViewControllerContextTransitioning) {
        let from = transitionContext.viewController(forKey: .from)!
        let to = transitionContext.viewController(forKey: .to)!
        let toFinalFrame = transitionContext.finalFrame(for: to)
        container.insertSubview(to.view, aboveSubview: from.view)
        to.view.frame = CGRect(x: 0, y: toFinalFrame.height, width: toFinalFrame.width, height: toFinalFrame.height)
        UIView.animate(withDuration: duration, animations: {
            to.view.frame = CGRect(x: 0, y: 0, width: toFinalFrame.width, height: toFinalFrame.height)
        }) { (_) in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        }
    }
    
    private func dismiss(duration: TimeInterval, container: UIView, transitionContext: UIViewControllerContextTransitioning) {
        let from = transitionContext.viewController(forKey: .from)!
        let fromFinalFrame = transitionContext.finalFrame(for: from)
        UIView.animate(withDuration: duration, animations: {
            from.view.frame = CGRect(x: 0, y: container.bounds.height, width: fromFinalFrame.width, height: fromFinalFrame.height)
        }) { (_) in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        }
    }
}