问如何在Firebase中向用户发送验证电子邮件之前注销用户

EN

func signUp(with email: String, password: String, firstName: String, lastName: String) {
    self.presentActivityView()
    Auth.auth().createUser(withEmail: email, password: password) {[unowned self] (user, error) in
        DispatchQueue.main.async { [unowned self] in
            self.dismissActivityView()
            if let err = error {
                self.addAlertController(title: "Error!", message: err.localizedDescription)
            } else {
                let changeReq = Auth.auth().currentUser?.createProfileChangeRequest()
                changeReq?.displayName = firstName + " " + lastName
                if let url = self.profilePicURLString {
                    changeReq?.photoURL = URL(string: url)
                }
                changeReq?.commitChanges(completion: { (error) in
                    if error == nil {
                        //Profile updated successfully
                    }else {
                        //Profile not updated successfully
                    }
                })
                Auth.auth().currentUser?.sendEmailVerification(completion: { (error) in
                    if error == nil {
                        //Verification initiated successfully
                    }else {
                        print("Error: \(error)")
                    }
                })
                let vc = MainStoryboard.instantiateViewController(withIdentifier: "SNStoryFeedController") as! SNStoryFeedController
                let nc = UINavigationController(rootViewController: vc)
                UIApplication.shared.keyWindow?.rootViewController = nc
            }
        }
    }
}