Swift3 如何更改导航控制器的根控制器在屏幕上的显示方式？

导航控制器不是初始视图控制器。它在初始VC中实例化，并随根控制器（第二个VC）一起提供。当我调用present view controller函数时，我无法改变这个新VC的呈现方式，它总是从底部显示。我没有找到如何使它从右到左。我试着把第二个VC打电话给modalPresentaionStyle的人换成导航控制，然后再换回来，但没有改变。 代码清单如下。谢谢你的帮助

@objc fileprivate func showRegisterScreen() { 
    let registerAccountVC = RegisterAccountVC()
    let navigationController = UINavigationController(rootViewController: registerAccountVC)
    navigationController.modalPresentationStyle = .pageSheet
    present(navigationController, animated: true, completion: nil)
}

let transition = CATransition.init()
transition.duration = 0.4
transition.timingFunction = CAMediaTimingFunction.init(name: kCAMediaTimingFunctionEaseInEaseOut)
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromRight
view.window?.layer.add(transition, forKey: nil)
present(navigationController, animated: false, completion: nil)

---

这将从右向左添加自定义动画

let transition = CATransition.init()
transition.duration = 0.4
transition.timingFunction = CAMediaTimingFunction.init(name: kCAMediaTimingFunctionEaseInEaseOut)
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromRight
view.window?.layer.add(transition, forKey: nil)
present(navigationController, animated: false, completion: nil)