while pushing on second VC getting error stack not updated

Question

i am creating a Swift app and with this app user can login with their email so for that i have created webservice and user can able to login successfully but after login when i got success response i am redirecting back to Home screen of app but pushViewController not working i am getting below error

pushViewController:animated: called on while an existing transition or presentation is occurring; the navigation stack will not be updated.

below is my code for login with api integration and redirecting code

 let params = ["email":txtEmail.text!,"password":txtPassword.text! ,"device_type":"iOS" , "device_token": deviceid]
            print(params)
            self.viewMainSpinner.isHidden = false
            self.viewInnerSpinner.startAnimating()

            Alamofire.request(login, method: .post, parameters: params).responseJSON(completionHandler: {(response) in
                print(response.result)
                switch response.result{

                case.success(let value):
                    let json = JSON(value)

                    let success = json["success"].stringValue

                    if success == "1"{

                        let message = json["message"].stringValue

                        let data = json["data"]
                        let accesstkn = data["access_token"].stringValue
                        let userid = data["user_id"].stringValue
                        let firstName = data["first_name"].stringValue


                        let preferences = UserDefaults.standard

                        let uid = "u_id"
                        let acctkn = "acc_tkn"
                        let f_name = "first_name"

                        let u_id = userid
                        let acc_tkn = accesstkn
                        let firName = firstName


                        preferences.set(u_id, forKey: uid)
                        preferences.set(acc_tkn, forKey: acctkn)
                        preferences.set(firName, forKey: f_name)


                        Loaf(message, state: .success, sender: self).show()

                        let storyboard = UIStoryboard(name: "Functional", bundle: nil)
                        let VC = storyboard.instantiateViewController(withIdentifier: "CustomTabBarViewController") as! CustomTabBarViewController
                        self.navigationController?.interactivePopGestureRecognizer?.isEnabled = false
                        self.navigationController?.pushViewController(VC, animated: true)
                    }else{
                        let message = json["message"].stringValue
                        Loaf(message, state: .error, sender: self).show()
                    }
                case.failure(let error):
                    Loaf(error.localizedDescription, state: .error, sender: self).show()
                }
                self.viewMainSpinner.isHidden = true
                self.viewInnerSpinner.stopAnimating()
            })

please check here is my login code and after login i am not able to redirect on home screen

please tell me why this is happing ?

Answer 1

Seem like show() method implementation is performing navigation related action in below line of code:

Loaf(message, state: .success, sender: self).show()

and quickly after that you are performing push on navigation controller.

Try commenting above line of code and try to login.