Question

我正在编写一个基本的iOS应用来测试我的Swift知识并继续练习。在我的应用程序中，用户键入婴儿的名称，然后打开或关闭开关以设置性别/性别，并更改系统颜色。之后，该名称用于在以下代码块中填写名为＆＃34; firstWords＆＃34;的UITextView：

// Save name entered into text field
@IBAction func saveSettings(_ sender: UIButton) {
    nameLabel.text = nameTextField.text
    if nameTextField.text == "" {
        showMessage()
        nameLabel.text = "Baby Name"
    }
    nameTextField.resignFirstResponder()
    let nameHolder: String! = nameLabel.text
    if boyGirlSwitch.isOn {
        let sex = ("boy", "his", "he", "Boy", "His", "He")
    } else {
        let sex = ("girl", "her", "she", "Girl", "Her", "She")
    }
    firstWords.text = "Wow, " + nameHolder + " has so much to look forward to!" + (sex.5) + " will do so many great things!"
}

我在(sex.5)内的元组firstWords上一直收到错误消息：＆＃34; Use of unresolved identifier 'sex'＆＃34;

据我了解，常量sex是在if语句中声明的，编译器确实以任何方式通过它，因此它确实被识别并声明。 问题：为什么我收到错误？

提前致谢！这是我的代码的屏幕截图： Screenshot of block of code as described above, including the compiler/build-error

Answer 1

这是一个范围问题。 sex仅在else子句中可用。

您可以像这样修复

// Save name entered into text field
@IBAction func saveSettings(_ sender: UIButton) {
    nameLabel.text = nameTextField.text
    if nameTextField.text == "" {
        showMessage()
        nameLabel.text = "Baby Name"
    }
    nameTextField.resignFirstResponder()
    let nameHolder: String! = nameLabel.text
    var sex : (String, String, String, String, String, String)
    if boyGirlSwitch.isOn {
        sex = ("boy", "his", "he", "Boy", "His", "He")
    } else {
        sex = ("girl", "her", "she", "Girl", "Her", "She")
    }
    firstWords.text = "Wow, " + nameHolder + " has so much to look forward to!" + (sex.5) + " will do so many great things!"
}

这种方式sex在整个IBAction的范围内定义，最终可用。

如果您使用默认值预先声明它，也可以跳过一个条件：

// Save name entered into text field
@IBAction func saveSettings(_ sender: UIButton) {
    nameLabel.text = nameTextField.text
    if nameTextField.text == "" {
        showMessage()
        nameLabel.text = "Baby Name"
    }
    nameTextField.resignFirstResponder()
    let nameHolder: String! = nameLabel.text
    var sex = ("girl", "her", "she", "Girl", "Her", "She")
    if boyGirlSwitch.isOn {
        sex = ("boy", "his", "he", "Boy", "His", "He")
    }
    firstWords.text = "Wow, " + nameHolder + " has so much to look forward to!" + (sex.5) + " will do so many great things!"
}

维基百科上有一篇关于变量范围的文章：https://en.wikipedia.org/wiki/Scope_(computer_science)

@IBAction函数中未解决的标识符错误

1 个答案: