试图将int从文本字段转换为数组swift 4

Question

I am developing an iOS app, I am trying to use a textfield and a button to submit an integer into an array so that I can store it using 'userdefaults'. So far I have got a different textfield adding the String entered into the array and storing it in the user defaults.

     @IBAction func workBtn(_ sender: Any)
{
    let kidnum: Int = Int(enteredScore.text!)!
    kidName.append(enteredName.text!)
    kidScore.append(kidnum)

    enteredName.text?.removeAll()
    enteredScore.text?.removeAll()
}


@IBAction func finishBtn(_ sender: Any)
{
    let userDefaults = UserDefaults.standard
    userDefaults.set(kidName, forKey: "Pupil Name")
    userDefaults.set(kidScore, forKey: "Pupil Score")

    userDefaults.synchronize()
}

workBtn is the add button I am using, I did also try to use a string as I don't actually need the integer for working out but just to display a score but I could not get it to save, I am passing it through it to be displayed on a table view controller cell. Thanks

I am using Xcode 9.1 Swift 4, Thanks.

Edit*** After running it I got an error in this function on the line marked stating "Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value"

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
    let userDefaults = UserDefaults.standard
    var nameArray: [String] = userDefaults.object(forKey:"Pupil Name") as! [String]
    //Error occurring on next line.
    var scoreArray: [Int] = userDefaults.object(forKey: "Pupil Score") as! [Int]

    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
    cell.textLabel?.text = "\(nameArray[indexPath.item]) -Score: \(scoreArray[indexPath.item])"

    userDefaults.synchronize()

    return cell
}

Answer 1

The error you are receiving means you are accessing a nil value somewhere where you don't expect it. This is most likely by force-unwrapping some value which you do constantly in your code. Try avoiding the usage of ! . In your code it might be any of lines such as let kidnum: Int = Int(enteredScore.text!)! but it might also be some field is missing connection for instance and is declared as @IBOutlet weak var enteredName: UITextField! which unfortunately is a default.

To debug this you might want to enable exception breakpoint: In navigator on your left side of Xcode on the top there is an icon for breakpoints (a bullet). Select it and then check on the bottom left and find a "+" button, press it and select "Exception breakpoint...". Then simply click away. Now your execution will stop whenever an exception like yours is hit. Run your project and find the line, object that is nil and should not be. Then fix your issue.

But in general try writing your code more like the following:

    @IBOutlet private weak var scoreTextField: UITextField?
    @IBOutlet private weak var nameTextField: UITextField?

    private typealias NameScore = (name: String, score: Int)
    private var dataArray: [NameScore] = [NameScore]()

    override func viewDidLoad() {
        super.viewDidLoad()
        loadData()
    }

    @IBAction private func workPressed() {
        let scoreValue: Int? = {
            guard let string = scoreTextField?.text, let integer = Int(string) else {
                return nil
            }
            return integer
        }()

        guard let score = scoreValue else {
            print("Could not parse integer value") // TODO: Show alert view
            return
        }

        guard let name = nameTextField?.text else {
            print("Name was not provided") // TODO: Show alert view
            return
        }

        dataArray.append((name: name, score: score))

        // Clear text fields
        scoreTextField?.text = nil
        nameTextField?.text = nil
    }


    @IBAction private func finishPressed() {
        saveData()
    }

    private let pupilNameKey: String = "name"
    private let pupilScoreKey: String = "score"
    private let pupilDataKey: String = "pupil_data"

    private func saveData() {
        // Let's convert data into something that makes more sense for safety
        let dataToSave: [[String: Any]] = dataArray.map { object in
            return [pupilNameKey: object.name,
                    pupilScoreKey: object.score]
        }

        UserDefaults.standard.set(dataToSave, forKey: pupilDataKey)
        UserDefaults.standard.synchronize()
    }

    private func loadData() {
        guard let savedData = UserDefaults.standard.value(forKey: pupilDataKey) as? [[String: Any]] else {
            // No saved data or incorrect format
            return
        }

        dataArray = savedData.flatMap { descriptor in
            guard let name = descriptor[pupilNameKey] as? String, let score = descriptor[pupilScoreKey] as? Int else {
                return nil // Could not parse this object
            }
            return (name: name, score: score)
        }
    }

And table view:

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dataArray.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        let dataObject = dataArray[indexPath.row]
        cell.textLabel?.text = "\(dataObject.name) -Score: \(dataObject.score)"
        return cell
    }

I hope the code speaks for itself on how to avoid force unwrapping and also how to pack your data.