一个 NSTimer ，时间间隔将检查用户是否已经过验证，然后在验证完成后终止计时器。

How i implemented this feature was to add a NSTimer, with time interval which would check if the user has been verified and then terminate the timer when the verification was done.

var verificationTimer : Timer = Timer()    // Timer's  Global declaration

self.verificationTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(LoginViewController.checkIfTheEmailIsVerified) , userInfo: nil, repeats: true)

函数检查您当前的用户状态： -

Function to check your current user state:-

func checkIfTheEmailIsVerified(){

    FIRAuth.auth()?.currentUser?.reload(completion: { (err) in
        if err == nil{

            if FIRAuth.auth()!.currentUser!.isEmailVerified{

                let feedVCScene = self.navigationController?.storyboard?.instantiateViewController(withIdentifier: "ViewControllerVC_ID") as! ViewController
                self.verificationTimer.invalidate()     //Kill the timer
                self.navigationController?.pushViewController(feedVCScene, animated: true)
                // Segueing to the next view(i prefer the instantiation method).
            } else {

                print("It aint verified yet")

            }
        } else {

            print(err?.localizedDescription)

        }
    })

}