Question

我收到此错误，我一生都无法弄清为什么它返回nil值。

致命错误：在隐式展开可选值时意外发现nil

错误发生在：

} else {
    gameInfo.player = players
    self.performSegue(withIdentifier: "ServerView", sender: self)
}

以下是我从表视图控制器开始的全套代码。

class PlayerSelectViewController: UIViewController {

    @IBOutlet weak var playerButton: UIButton!
    @IBOutlet weak var playersTextBox: UITextField!

    var gameInfo:GameInfo!
    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func cancelBtnClicked(_ sender: Any) {
        self.navigationController?.popToRootViewController(animated: true)
    }

    @IBAction func okBtnClicked(_ sender: Any) {
        guard let players = Int(playersTextBox.text!) else {
            makeAlert(title: "Enter a Number", message: "Please enter a number and then press Ok")
            return
        }
        if players < 2 {
            makeAlert(title: "Incorrect Number", message: "Please input more than \(playersTextBox.text!)")
        } else if players > 50 {
            makeAlert(title: "Incorrect Number", message: "Please input less than \(playersTextBox.text!)")
        } else {
            gameInfo.player = players
            self.performSegue(withIdentifier: "ServerView", sender: self)
        }
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        let playerController = segue.destination as! ServerSelectViewController
        playerController.gameInfo = gameInfo
    }


    func makeAlert (title: String, message: String) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertController.Style.alert)

        alert.addAction(UIAlertAction(title: "Ok", style: UIAlertAction.Style.default, handler: {(action) in
            alert.dismiss(animated: true, completion: nil)}))
        self.present(alert, animated: true, completion: nil)
    }

这是我的模特。

class GameInfo: Codable {
    var player: Int
    var numberPicked: Int
    var datePlayed: Date
    var winner: String
    var turn: Int

    init(player: Int, numberPicked: Int, datePlayed: Date, winner: String, turn: Int) {
        self.player = player
        self.numberPicked = numberPicked
        self.datePlayed = datePlayed
        self.winner = winner
        self.turn = turn
    }


    static func loadGameInfo() -> [GameInfo] {
        return []
    }


    static let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

    static let archiveURL = documentsDirectory.appendingPathComponent("gameInformation").appendingPathExtension("plist")

    static func saveToFile(gameInformation: [GameInfo]) {
        let propertyListEncoder = PropertyListEncoder()
        let gameInfo = try? propertyListEncoder.encode(gameInformation)

        try? gameInfo?.write(to: archiveURL, options: .noFileProtection)
    }

    static func loadFromFile() -> [GameInfo]? {
        guard let gameInfo = try? Data(contentsOf: archiveURL) else { return nil }

        let propertyListDecoder = PropertyListDecoder()

        return try? propertyListDecoder.decode(Array<GameInfo>.self, from: gameInfo)
    }
}

Answer 1

致命错误：意外发现nil ，同时隐式展开一个可选值

因此请检查代码中隐式展开的可选内容。

您的选择似乎是：

hanoi(3,"a","b","c")

哪个从未分配过值？

致命错误：意外发现nil，同时隐式展开一个Optional值-无法弄清楚为什么它为nil

1 个答案: