Question

我尝试了以下简单的卡示例，但在尝试访问Array属性时一直出错。特别是在func中，getRandomCard（）卡在单击“翻转”按钮后变得无法访问。行为不一致，有时在第一次单击按钮时会发生错误，而在其他时候可以在错误发生前几次单击按钮。我究竟做错了什么？感谢您的任何见解。

//Class PlayingCardDeck
import Foundation

let validSuits = ["♣️", "♦️", "♥️", "♠️"]
let maxRank = 13

class PlayingCardDeck {
    var cards: [PlayingCard] = []

    init() {
        for suit in validSuits {
            for rank in 1...maxRank {
                var card = PlayingCard()
                card.suit = suit
                card.rank = rank
                self.addCard(card)
            }
        }
    }

    func addCard(aCard: PlayingCard) {
        cards.append(aCard)
    }

    func getRandomCard() -> PlayingCard {
        let idx = Int(arc4random()) % cards.count
        let retCard = cards[idx]
        cards.removeAtIndex(idx)
        return retCard
    }
}

//Class PlayingCard
import Foundation

let rankStrings = ["?", "A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"]

class PlayingCard {    
    var suit = "?"
    var rank = 0

    var contents: String {
        get {
            return rankStrings[rank] + suit
        }
    }
}


//Class ViewController
import UIKit

class ViewController: UIViewController {

    var myDeck = PlayingCardDeck()

    @IBOutlet weak var cardLabel: UILabel!

    @IBAction func flipButton(sender: UIButton) {
        let s = myDeck.getRandomCard().contents
        cardLabel.text = s
    }
}

Answer 1

我敢打赌，尽管有错误消息，但您实际上看到了整数溢出错误。请尝试使用arc4random_uniform()：

 let idx = Int(arc4random_uniform(UInt32(cards.count)))

Swift数组访问不好

1 个答案: