Question

我正在尝试制作一个测验应用，我想添加最高分，但是当我点击正确的答案按钮时，coinLabel有Matcoin = 10文字。然后我再次点击正确的答案按钮，它应该包含文字Matcoin = 20，但它有Matcoin = 10。它没有添加分数。

这是我的代码：

var coin = 0
func addCoin() {

    if soruSayisi >= 1 && soruSayisi <= 12 {
        //if the number of questions is between 1 and 12
        coin = coin + 10

    else {
        print("error")
    }

    UserDefaults.standard.set(coin, forKey: "coin")
    UserDefaults.standard.synchronize()

    coinLabel.text = NSString(format: "Matcoin =  %i", coin) as String

}
@IBAction func AbuttonClicked(_ sender: Any) {

    if "A" == cvpLbl {

        addCoin()
        //correct answer
    }


override func viewWillAppear(_ animated: Bool) {

    let coinString = String(UserDefaults.standard.integer(forKey: "coin"))
    coinLabel.text = "Matcoin = \(coinString)"
}

Answer 1

原因是当您调用addCoin（）时没有从userDefaults读取硬币值

func addCoin() {

    coin = UserDefaults.standard.integer(forKey: "coin")

    if soruSayisi >= 1 && soruSayisi <= 12 {

        coin = coin + 10

    else {

        print("error")
        return
    }

    UserDefaults.standard.set(coin, forKey: "coin")

    coinLabel.text = String(coin)
}

Answer 2

在viewWillAppear中读取UserDefaults的值，将其分配给coin和标签。 请勿忘记致电super

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    coin = UserDefaults.standard.integer(forKey: "coin")
    coinLabel.text = "Matcoin = \(coin)"
}

在addCoin()中，首先检查soruSayisi是否在1..12范围内。如果是，则将硬币加10，将其写入UserDefaults并更新标签。如果UserDefaults是最新的，则从coin读取的行是多余的。代码使用模式匹配运算符~=来检查范围，使用添加赋值运算符 +=来增加值：
```
func addCoin() {
    if  1...12 ~= soruSayisi {
        coin += 10
        UserDefaults.standard.set(coin, forKey: "coin")
        coinLabel.text = "Matcoin = \(coin)"
    } else { print("error") }
}
```

Answer 3

为什么不将硬币作为计算属性，所以当你使用它时，它会自动获取最新值并更新标签？

var coin = 0 {
  didSet {
    coinLabel.text = "Matcoin =  \(coin)"
  }
}

func addCoin() {
    if soruSayisi >= 1 && soruSayisi <= 12 {
        //if the number of questions is between 1 and 12
        coin += 10
    }

    UserDefaults.standard.set(coin, forKey: "coin")
}

@IBAction func aButtonClicked(_ sender: UIButton) {

    if "A" == cvpLbl {

        addCoin()
        //correct answer
    }
}

override func viewWillAppear(_ animated: Bool) {
    coin = UserDefaults.standard.integer(forKey: "coin"))
}

我无法使用NSUserDefaults

3 个答案: