Swift - 访问结构体 [英] Swift - accessing structs

问题描述

如果我有一个如下定义的结构：

If I have a struct defined like this:

struct Cat {
    static let Siamese = "Siamese"
    static let Tabby = "Tabby"
    static let Fluffy = "Fluffy"

    static func cat () -> [String] {
        return [Siamese, Tabby, Fluffy]
    }
}

为什么我无法访问它？

var cat:Cat = Cat.Siamese //"NSString" is not a subtype of Cat

推荐答案

您正在尝试将一个String赋给一个定义为 Cat 的变量。这就是为什么你得到一个错误。

You are trying to assign a String to a variable defined as a Cat. That is why you are getting an error.

您的 Cat struct中的所有静态成员都是字符串，而不是 Cat s。

All of your static members in your Cat struct are strings, not Cats.

此外，你的结构没有任何实际的成员。我想你打算有一个名字属性：

Also, your struct doesn't have any actual members. I think you are intending to have a name property:

struct Cat {
    let name: String

    static let Siamese = Cat(name: "Siamese")
    static let Tabby = Cat(name: "Tabby")
    static let Fluffy = Cat(name: "Fluffy")
}

var cat : Cat = Cat.Siamese

您可以更好地使用枚举：

You may be better served with an enum:

enum Cat : String {
    case Siamese = "Siamese"
    case Tabby = "Tabby"
    case Fluffy = "Fluffy"
}

var cat: Cat = .Tabby
println(cat.toRaw()) // "Tabby"

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