Perform Segue from another class with helper function

Question

I have two classes, ChargeCustomer and TwelvethViewController. In TwelvethViewController I have a func goNextView() which should perform a segue to next view controller when called. goNextView() is called from class ChargeCustomer inside a Alamofire completion handler. The problem is that this function goNextView() is never called and I can't figure out why. I tried to make it work based on this answer on stackoverflow Perform Segue From Another Swift File via a class function

 class TwelvethViewController:UIViewController {

  //when this func is called, it should segue to Thiretheen
  func goNextView() {
    performSegue(withIdentifier: "twelvethToThiretheen", sender: self)
      }
 }

 class ChargeCustomer {

    //send a post request to the server
    Alamofire.request(urlString, method: .post, parameters: params, encoding: JSONEncoding.default, headers: ["Content-Type":"application/json"]).responseJSON {
        (response: DataResponse<Any>) in
                print("received reply from ALamofire") //prints string

           //perform segue to Thireteen View Controller
        func showNextView(fromViewController:TwelvethViewController) {
              print("went through")      //doesn't print
                 fromViewController.goNextView()
                    print("it has segued")      //doesn't print
           }      
      } ///end of Alamofire
   } //end of chargeUsingCustomer

Updated answer according to José Neto

 class ChargeCustomer {
 //create instance of the viewcontroller that has segue with identifier    twelvethToThiretheen
   let twelvethVC = TwelvethViewController()

    //send a post request to the server
    Alamofire.request(urlString, method: .post, parameters: params, encoding: JSONEncoding.default, headers: ["Content-Type":"application/json"]).responseJSON {
        (response: DataResponse<Any>) in
                print("received reply from ALamofire") //prints string

//perform segue to Thirteen View Controller
   //crashes: <CleaningApp.TwelvethViewController: 0x7fd4e16ad2a0>) has no 
     //segue with identifier 'twelvethToThiretheen''
 self.showNextView(fromViewController: self.twelvethVC )
      } //end of Alamofire

    //perform segue to Thireteen View Controller
   func showNextView(fromViewController:TwelvethViewController) {
        fromViewController.goNextView()      
       }      
} //end of chargeUsingCustomer

Answer 1

You have to instantiated the storyBoard that you want then the TwelvethViewController and finally you can push. Like this:

let storyBoard = UIStoryboard(name: "youStoryBoard", bundle: nil) 
let vc = storyboard?.instantiateViewController(withIdentifier: "youVCIndentifier") as! TwelvethViewController 
self.navigationController?.pushViewController(vc, animated: true)