how to send same OTP to mobile number and Email with firebase

Question

when I'm tried to send firebase otp to mail I got string formed

func sendOtpToMobile() {
  guard let phonenumber = phoneNumberTextField.text else { return }
  PhoneAuthProvider.provider().verifyPhoneNumber(phonenumber, uiDelegate: nil) { [self] (verificationID , error) in
    if error == nil {
      UserDefaults.standard.set(verificationID, forKey: "verificationID")
      UserDefaults.standard.synchronize()
    } else {
      print("unable to get verification code" , error?.localizedDescription)
    }
  }
}