Execute action when back bar button of UINavigationController is pressed

https://stackoverflow.com/questions/27713747/execute-action-when-back-bar-button-of-uinavigationcontroller-is-pressed

self.navigationItem.hidesBackButton = true

        let newBackButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.plain, target: self, action: #selector(Quoterequestsend.back(sender:)))

        self.navigationItem.leftBarButtonItem = newBackButton

  func back(sender: UIBarButtonItem) {

        

        let storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

        

        let vc = storyBoard.instantiateViewController(withIdentifier: "viewcontroller") as! viewcontroller

        

        self.navigationController?.pushViewController(vc, animated: true)

    }