每次按下按钮时，如何从标签“26”中减去 1？ （斯威夫特初学者）

Question

斯威夫特初学者

每次按下“交易”按钮时，我都想从值为“26”的标签中减去 1。我将其转换为 Int 吗？以及如何添加计算？

我编写了cardsAmount.text = "25"，它有效。但是每次按下按钮时都需要减1，而不是硬编码。

另外，以后我想加号。

谢谢！

class ViewController: UIViewController {

    @IBOutlet weak var leftPile: UIImageView!

    @IBOutlet weak var rightPile: UIImageView!

    @IBOutlet weak var cardsAmount: UILabel!

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

        }


    @IBAction func deal(_ sender: Any) {

        let shuffled = (2...53).shuffled()
        let leftNumber = shuffled[0]
        let rightNumber = shuffled[1]

        //cardsAmount.text = "25"

        leftPile.image = UIImage(named: "c\(leftNumber)")

        rightPile.image = UIImage(named: "c\(rightNumber)")


    }
    .
    .
    .
}

Answer 1

您可以使用属性观察器。

var number: Int = 26 {
    didSet {
        if number > 0 {
        self.cardsAmount.text = "\(number)"
        }
    }
}

@IBAction func deal(_ sender: Any) {
    let shuffled = (2...53).shuffled()
    let leftNumber = shuffled[0]
    let rightNumber = shuffled[1]

    number -= 1 // whenever number value changes, didSet (property observer) will be called

    leftPile.image = UIImage(named: "c\(leftNumber)")
    rightPile.image = UIImage(named: "c\(rightNumber)")
}

Answer 2

我认为您应该添加variable，因为您是初学者。使用这个：

var initialNumber: Int = 1
var number: Int = 26

@IBAction func deal(_ sender: Any) {

    let shuffled = (2...53).shuffled()
    let leftNumber = shuffled[0]
    let rightNumber = shuffled[1]

    number = number - initialNumber
    cardsAmount.text = "\(number)" //This is to subtract. Now you can check if it is a negative number and perform operations ahead using if else

    leftPile.image = UIImage(named: "c\(leftNumber)")

    rightPile.image = UIImage(named: "c\(rightNumber)")


}

您可以按照相同的方法添加数字。如果你想保存initialNumber 那么你可以写initialNumber = initialNumber + 1 然后使用它。如果您对此答案有任何疑问，请告诉我。