我有这个功能来呈现登录/注册模态视图Controller。传递的参数必须是UIViewController(UIViewController代表方法，AuthViewControllerDelegate代表方法)staticfunccheckAuthError(controller:UIViewController,err:NSError){iferr.code==401{letauthViewController=viewControllerWithIdentifier("AuthViewController")as!AuthViewControllerauthViewControl