How to validate quiz answers using Airtable API in Swift iOS app

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1

I’m building a vocabulary quiz app in Swift and using Airtable as my backend database. I managed to get the questions and choices displaying correctly, but I’m having trouble with answer validation.

Here’s my current code for loading quiz data:

func loadQuizData() {
    let endpoint = "https://api.airtable.com/v0/appXYZ123/QuizTable?maxRecords=15&view=Main"
    let token = "myToken"
    let requestURL = URL(string: endpoint)!
    var apiRequest = URLRequest(url: requestURL)
    apiRequest.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
    
    URLSession.shared.dataTask(with: apiRequest) { (responseData, urlResponse, requestError) in
        let jsonDecoder = JSONDecoder()
        guard let responseData = responseData else { return }
        do {
            let quizData = try jsonDecoder.decode(QuizResponse.self, from: responseData)
            DispatchQueue.main.async {
                self.questionCounter.text = "Question \(self.currentQuestion+1)"
                self.questionText.text = quizData.records[self.currentQuestion].fields.questionText
                self.choiceOne.setTitle(quizData.records[self.currentQuestion].fields.choiceOne, for: .normal)
                self.choiceTwo.setTitle(quizData.records[self.currentQuestion].fields.choiceTwo, for: .normal)
                self.choiceThree.setTitle(quizData.records[self.currentQuestion].fields.choiceThree, for: .normal)
                self.choiceFour.setTitle(quizData.records[self.currentQuestion].fields.choiceFour, for: .normal)
            }
        } catch {
            print("Error: \(error)")
        }
    }.resume()
}

The problem happens when I try to check if the user picked the right answer. My quiz data becomes nil and crashes the app. How can I properly store and access the correct answers for comparison?

2

Your app crashes because you’re trying to access quiz data that’s already been deallocated. You can’t just use it once in the network callback - you need to store it properly.

Add a property to hold your quiz data:

var quizRecords: [QuizRecord] = []

Update your loadQuizData function to actually store the data:

let quizData = try jsonDecoder.decode(QuizResponse.self, from: responseData)
self.quizRecords = quizData.records
DispatchQueue.main.async {
    self.displayQuestion()
}

Make a separate function for displaying questions:

func displayQuestion() {
    guard currentQuestion < quizRecords.count else { return }
    let record = quizRecords[currentQuestion]
    questionCounter.text = "Question \(currentQuestion+1)"
    questionText.text = record.fields.questionText
    choiceOne.setTitle(record.fields.choiceOne, for: .normal)
    // ... other choices
}

For answer validation, compare against your stored data:

func validateAnswer(_ selectedChoice: String) -> Bool {
    return selectedChoice == quizRecords[currentQuestion].fields.correctAnswer
}

This pattern crashes apps all the time. Keep your data alive beyond the network call and you’ll be fine.