Question

我创建了一个名为playAgainButton的按钮，这是一个允许重置Tic Tac Toe游戏的按钮，这样你就可以再玩一次......但这个playAgainButton正在崩溃我的应用程序，而不是重置游戏为默认gameState。

import UIKit

class ViewController: UIViewController {

    //All the odd numbers will be noughts & even will be crosses
    var goNumber = 1
    var winner = 0

    //0 = empty, 1 = nought, 2 = cross
    var gameState = [0, 0, 0, 0, 0, 0, 0, 0, 0]

    let winningCombinations = [[0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6]]

    @IBOutlet weak var button0: UIButton!
    @IBOutlet weak var label: UILabel!
    @IBOutlet weak var playAgain: UIButton!

    @IBAction func playAgainButton(sender: AnyObject) {

        goNumber = 1

        winner = 0

        gameState = [0, 0, 0, 0, 0, 0, 0, 0, 0]

        label.center = CGPointMake(label.center.x - 400, label.center.y)

        playAgain.alpha = 0

        var button : UIButton

        for var i  = 0; i < 9; i++ {

        button = view.viewWithTag(i) as! UIButton

        button.setImage(nil, forState: .Normal)

        }

    }
    @IBAction func buttonPressed(sender: AnyObject) {

        var image = UIImage()

        if (gameState[sender.tag] == 0) && winner == 0 {

        println(sender.tag)

        if (goNumber % 2 == 0 ) {

        image = UIImage(named: "cross.png")!
            gameState[sender.tag] = 2
        } else {

        image = UIImage(named: "nought.png")!
            gameState[sender.tag] = 1
        }

            for combination in winningCombinations {

                if (gameState[combination[0]] == gameState[combination[1]] && gameState[combination[1]] == gameState[combination[2]]) && gameState[combination[0]] != 0{

                    winner = gameState[combination[0]]
                }

            }

            if (winner != 0) {

                println("We have a winner")

                if (winner == 1) {

                    label.text = "Noughts has won"
                    label.backgroundColor = UIColor .blueColor()
                } else {
                    label.text = "Crosses has won"
                    label.backgroundColor = UIColor .blueColor()
                }

                UIView.animateWithDuration(1, animations: {
                    self.label.center = CGPointMake(self.label.center.x + 400, self.label.center.y)

                    self.playAgain.alpha = 1
                })
            }

        goNumber++
        sender.setImage(image, forState: .Normal)

        }
    }

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

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func viewDidAppear(animated: Bool) {
        label.center = CGPointMake(label.center.x - 400, label.center.y)
        playAgain.alpha = 0
    }
}

Answer 1

这仅表示viewWithTag()返回的视图不是UIButton的实例，而只是UIView的实例。强制转换在运行时失败，并引发异常。

我不确定多个视图具有相同标记时返回的内容，但请确保您没有将相同的标记分配给另一个非按钮视图。

Answer 2

标签属性的默认值是0.你的循环从i = 0开始作为标签搜索解释你的错误，因为在这种情况下你会得到第一个不是按钮的视图还要使用内省来确保视图类型为按钮

if object is UIButton {
    // object is of type UIButton
} else {
    // object is not of type UIButton
}

在Swift中触摸时按钮崩溃应用程序

2 个答案: