CodeViewController - complete

CodeViewController.swift

import UIKit

class CodeViewController: UIViewController {

    @IBOutlet weak var codeTextField: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        title = "Enter Code"
        navigationItem.leftBarButtonItem = 
            UIBarButtonItem(title: "", style: .plain, target: self, action: nil)
        DispatchQueue.main.asyncAfter(deadline: .now() + 30) { [weak self] in
            self?.showCancelButton()
        }
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        codeTextField.text = ""
        codeTextField.becomeFirstResponder()
    }
    
    func showCancelButton() {
        navigationItem.leftBarButtonItem = 
            UIBarButtonItem(title: "Cancel", style: .plain, target: self, 
                            action: #selector(cancel))
    }
    
    @objc func cancel() {
        codeTextField.resignFirstResponder()
        SwiftSpinner.show("Cancelling your request")
        guard let requestId = UserDefaults.standard.value(forKey: 
        Constant.UserDefault.requestId) as? String else {
            goBack()
            return
        }
        VerifyService.shared.cancel(requestId: requestId, successResponse: { [weak self] in
            DispatchQueue.main.async {
                SwiftSpinner.hide()
                self?.goBack()
            }
        }) { [weak self] error in
            DispatchQueue.main.async {
                SwiftSpinner.show(duration: 1, title: "Something went wrong")
                self?.goBack()
            }
        }
    }
    
    internal func goBack() {
        UserDefaults.standard.removeObject(forKey: Constant.UserDefault.requestId)
        navigationController?.popViewController(animated: true)
    }

    
    @IBAction func codeChanged(_ sender: Any) {
        let textLength = codeTextField.text?.lengthOfBytes(using: .utf8) ?? 0
        if textLength >= 4 {
            checkPin()
        }
    }
    
    internal func checkPin(){
        codeTextField.resignFirstResponder()
        guard let code = codeTextField.text else {
            return
        }
        SwiftSpinner.show("Validating the code...")
        
        guard let requestId = UserDefaults.standard.value(forKey: 
            Constant.UserDefault.requestId) as? String else {
            DispatchQueue.main.async {
                SwiftSpinner.show(duration: 2, 
                                  title: "Something went wrong.\nPlease try again...", 
                                  animated: false)
            }
            return
        }
        
        VerifyService.shared.check(requestId: requestId, code: code, 
                                   successResponse: {
            DispatchQueue.main.async {
                SwiftSpinner.show(duration: 1, 
                                  title: "Validated successfully!", 
                                  animated: false)
                UserDefaults.standard.setValue(Date(), 
                    forKey: Constant.UserDefault.lastVerifiedAt)
                UserDefaults.standard.removeObject(forKey: 
                    Constant.UserDefault.requestId)
                DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
                    Router.navigateTo("home")
                }
            }
        }) { [weak self] error in
            DispatchQueue.main.async {
                SwiftSpinner.show(duration: 2, 
                                  title: "Something went wrong.\nPlease try again...", 
                                  animated: false)
                self?.codeTextField.text = ""
            }
            DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
                self?.codeTextField.becomeFirstResponder()
            }
        }
    }
    
}