firebase在通过google注册时不会发送电子邮件验证电子邮件

我使用firebase作为项目的后端来验证用户。每个用户注册后,我想发送一封验证电子邮件,以确认他们是一个真实的人和帐户持有人。我正在使用 AuthViewController 从 FirebaseUI 并附上了一个听众。下面是发送电子邮件验证的代码。我注意到当用户第一次注册而没有发送任何验证电子邮件时,google帐户返回为已经验证。

应用程序委托内部

    func authUI(_ authUI: FUIAuth, didSignInWith user: User?, error: Error?) {
        // handle user and error as necessary
        if let error = error{
            print("Error: \(error.localizedDescription)")
        }

        if let user = user{
        print("Signed in user: \(user.uid)")
            if user.isEmailVerified{
                print("The email has been verified")
                showHomeScreen()
            }
            else{
                print("User is not verified")
                user.sendEmailVerification(completion: {(err) in
                    if (err != nil){
                        print("Error in verifying email: \(err?.localizedDescription)")
                    }
                })
            }
            }
        }

视图控制器内部

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        handle = Auth.auth().addStateDidChangeListener { (auth, user) in
            // ...
            print("State changed")

            if Auth.auth().currentUser != nil && Auth.auth().currentUser!.isEmailVerified == true{
                print("User SignedIn")
                print("Email Verified")
            showHomeScreen()
            }
            else if user?.isEmailVerified == false{
                print("Email is not verified")
//                Auth.auth().currentUser?.sendEmailVerification { (error) in
//                    // Notify the user that the mail has sent or couldn't because of an error.
//                  //  showLoginScreen()
//                    if let error = error{
//                        print("Error sending Email Verification: \(error.localizedDescription)")
//                    }
//                    print("Email not verified")
//                }
            }
            else{
                print("User SignedOut")

                }
            }
        }