如何从Swift中的原始值获取enum ?

I'm trying to get enum type from raw value:

我试图从原始值中获取enum类型:

enum TestEnum: String {
    case Name
    case Gender
    case Birth

    var rawValue: String {
        switch self {
        case .Name: return "Name"
        case .Gender: return "Gender"
        case .Birth: return "Birth Day"
        }
    }
}

let name = TestEnum(rawValue: "Name")       //Name
let gender = TestEnum(rawValue: "Gender")   //Gender

But it seems that rawValue doesn't work for string with spaces:

但似乎rawValue对于带空格的字符串不起作用:

let birth = TestEnum(rawValue: "Birth Day") //nil

Any suggestions how to get it?

有什么建议吗?

3 个解决方案

#1

Too complicated, just assign the raw values directly to the cases

太复杂了，只需将原始值直接赋给这些情况

enum TestEnum: String {
  case Name = "Name"
  case Gender = "Gender"
  case Birth = "Birth Day"
}

let name = TestEnum(rawValue: "Name")!       //Name
let gender = TestEnum(rawValue: "Gender")!   //Gender
let birth = TestEnum(rawValue: "Birth Day")! //Birth

If the case name matches the raw value you can even omit it

如果大小写名称与原始值匹配，您甚至可以省略它

enum TestEnum: String {
  case Name, Gender, Birth = "Birth Day"
}

In Swift 3+ all enum cases are lowercased

在Swift 3+中，所有enum用小写形式表示

#2

Full working example:

完整的工作示例:

enum TestEnum: String {
    case name = "A Name"
    case otherName
    case test = "Test"
}

let first: TestEnum? = TestEnum(rawValue: "A Name")
let second: TestEnum? = TestEnum(rawValue: "OtherName")
let third: TestEnum? = TestEnum(rawValue: "Test")

print("\(first), \(second), \(third)")

All of those will work, but when initializing using a raw value it will be an optional. If this is a problem you could create an initializer or constructor for the enum to try and handle this, adding a none case and returning it if the enum couldn't be created. Something like this:

所有这些都可以工作，但是当使用原始值初始化时，它将是可选的。如果这是一个问题，您可以为enum创建一个初始化器或构造函数来尝试和处理它，添加一个none case并在未能创建enum时返回它。是这样的:

static func create(rawValue:String) -> TestEnum {
        if let testVal = TestEnum(rawValue: rawValue) {
            return testVal
        }
        else{
            return .none
        }
    }

#3

You can define enum like this -

你可以像这样定义enum -

enum TestEnum: String {
    case Name, Gender, Birth
}

或

enum TestEnum: String {
    case Name
    case Gender
    case Birth
}

you can provide an init method which defaults to one of the member values.

您可以提供一个init方法，该方法默认为其中一个成员值。

enum TestEnum: String {
    case Name, Gender, Birth

    init() {
        self = .Gender
    }
}

In the example above, TestEnum.Name has an implicit raw value of "Name", and so on.

在上面的示例中，TestEnum。Name具有“Name”之类的隐式原始值。

You access the raw value of an enumeration case with its rawValue property:

您可以使用其rawValue属性访问枚举实例的原始值:

let testEnum = TestEnum.Name.rawValue
// testEnum is "Name"
let testEnum1 = TestEnum() 
// testEnum1 is "Gender"

#1