Swift I can't move data with delegate - ios

Question

I'm trying to make a quiz application using the API, I can import the
data into the quizManager file, but I can't transfer the data to the
viewController, When I try to print in quizManger, I can print, but in viewController does not.
how do I move data to viewController?
QuizManager
import Foundation
protocol quizManagerDelegate {
func didUpdateQuiz(_ Quizmanager: QuizManager ,quiz: QuizModel)
}
struct QuizManager {
var delegate: quizManagerDelegate?
func performRequest(){
let urlString = "https://opentdb.com/api.php?amount=1&type=multiple"
if let url = URL(string: urlString){
let session = URLSession(configuration: .default)
let task = session.dataTask(with: url) { data, response, error in
if error != nil {
print(error!)
return
}
if let safeData = data{
if let quiz = self.parseJSON(quizdata: safeData){
delegate?.didUpdateQuiz(self, quiz: quiz)
}
}
}
task.resume()
}
}
func handle(data: Data?, response: URLResponse?, error: Error?) -> Void {
}
func parseJSON(quizdata: Data) -> QuizModel? {
let decoder = JSONDecoder()
do{
let decodedData = try decoder.decode(Welcome.self, from: quizdata)
let correct = decodedData.results?[0].correct_answer ?? "error"
let quest = decodedData.results?[0].question ?? "error"
let incorrect = decodedData.results?[0].incorrect_answers ?? ["error"]
let question = QuizModel(correctAnswer: correct, question: quest, falseAnswer: incorrect)
// print(question.correctAnswer)
// print(question.question)
// print(question.falseAnswer)
return question
} catch {
print(error)
return nil
}
}
}
QuizData
import Foundation
// MARK: - Welcome
struct Welcome: Codable {
let results: [Result]?
}
// MARK: - Result
struct Result: Codable {
let category: String?
let question, correct_answer: String?
let incorrect_answers: [String]?
}
QuizModel
import Foundation
struct QuizModel {
let correctAnswer : String
let question : String
let falseAnswer : [String]
}
ViewController
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var ChoiceButton4: UIButton!
#IBOutlet weak var ChoiceButton3: UIButton!
#IBOutlet weak var ChoiceButton2: UIButton!
#IBOutlet weak var ChoiceButton1: UIButton!
#IBOutlet weak var QuestionTextView: UITextView!
var quizMangager = QuizManager()
override func viewDidLoad() {
super.viewDidLoad()
QuestionTextView.layer.cornerRadius = 15
quizMangager.performRequest()
self.quizMangager.delegate = self
}
}
extension ViewController : quizManagerDelegate{
func didUpdateQuiz(_ Quizmanager: QuizManager, quiz: QuizModel) {
DispatchQueue.main.async {
print("***")
print(quiz.correctAnswer)
}
}
}

Answer 1

The problem is in viewDidLoad that lines
quizMangager.performRequest()
self.quizMangager.delegate = self
You call performRequest before to delegate it so when performRequest is called var delegate: quizManagerDelegate? is nil . Just call delegate before call function
override func viewDidLoad() {
super.viewDidLoad()
...
quizMangager.delegate = self
quizMangager.performRequest()
...
}

Answer 2

You have a slight mistake in your code. You just need to confirm the delegate first and then call its function .