ios - 错误？读取 IBAction 按钮内的变量

Question

我有一个 IBAction 需要从变量中读取。但是，当将变量放置在 viewDidLoad 之外时，我收到错误

Cannot use instance member 'animal' within property initializer; property initializers run before 'self' is available

我的代码如下。当我将变量移回 viewDidLoad 内部时，错误表明animalName 未声明

var animalName = (String(format: "%03d", animal.speciesId!))

@IBAction func megaKeyIBO(_ sender: Any) {
    animalName = (String(format: "%03d", animal.speciesId!)) + "-merg"
}

override func viewDidLoad() {
    super.viewDidLoad()

    //variable was originally here before moving to top
    var animalName = (String(format: "%03d", animal.speciesId!))
}

Answer 1

发生这种情况是因为您尝试在属性animal.speciesId之前初始化animalName!已初始化。一个简单的解决方法是这样的:

var animalName: String!

@IBAction func megaKeyIBO(_ sender: Any) {
    animalName = (String(format: "%03d", animal.speciesId!)) + "-merg"
}

override func viewDidLoad() {
    super.viewDidLoad()

    // Initialize on viewDidLoad
    animalName = (String(format: "%03d", animal.speciesId!))
}