arrays - swift 发现 fatal error 为零

Question

我收到以下错误消息:

"fatal error: unexpectedly found nil while unwrapping an Optional value"

当我运行这部分代码时:

 func askQuestion() {
    button1.setImage(UIImage(named: cards[0]), forState: .Normal)
    button2.setImage(UIImage(named: cards[1]), forState: .Normal)
    button3.setImage(UIImage(named: cards[2]), forState: .Normal)

    //title = cards[correctAnswer].uppercaseString
}

我不确定我做错了什么或出了什么问题。这是其余的代码:

import GameplayKit
import UIKit

class guessViewController: UIViewController {

@IBOutlet weak var button1: UIButton!
@IBOutlet weak var button2: UIButton!
@IBOutlet weak var button3: UIButton!
@IBOutlet weak var button4: UIButton!

var cards = [String]()
var score = 0
var correctAnswer = 0

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    cards += ["boots", "tired", "heart", "angry", "leaf", "sleepy", "apple", "chestnuts", "pumpkin", "rainbow"]

    askQuestion()

    //cards = GKRandomSource.sharedRandom().arrayByShufflingObjectsInArray(cards) as! [String]

}

func askQuestion() {
    button1.setImage(UIImage(named: cards[0]), forState: .Normal)
    button2.setImage(UIImage(named: cards[1]), forState: .Normal)
    button3.setImage(UIImage(named: cards[2]), forState: .Normal)

    //title = cards[correctAnswer].uppercaseString
}

@IBAction func buttonTapped(sender: UIButton) {

    if sender.tag == correctAnswer {
        score++
        print("correct")

    } else {

        score--
        print("incorrect")

        }
    }
}

Answer 1

试试这段代码。它会帮助你。

@IBOutlet weak var btn1: UIButton!
@IBOutlet weak var btn2: UIButton!

var cards  = [String] ()

override func viewDidLoad()
 {
   super.viewDidLoad()
   cards += ["11.jpg","1_home.jpg"]
 }


 @IBAction func btnAction(sender: AnyObject)
 {
    btn1.setBackgroundImage(UIImage(named: cards[0]), forState: UIControlState.Normal)
    btn2.setBackgroundImage(UIImage(named: cards[1]), forState: UIControlState.Normal)
 }