如何获取所有枚举值作为数组 [英] How to get all enum values as an array

问题描述

我有以下枚举.

enum EstimateItemStatus: Printable {
    case Pending
    case OnHold
    case Done

    var description: String {
        switch self {
        case .Pending: return "Pending"
        case .OnHold: return "On Hold"
        case .Done: return "Done"
        }
    }

    init?(id : Int) {
        switch id {
        case 1:
            self = .Pending
        case 2:
            self = .OnHold
        case 3:
            self = .Done
        default:
            return nil
        }
    }
}

我需要以字符串数组的形式获取所有原始值(例如["Pending", "On Hold", "Done"]).

I need to get all the raw values as an array of strings (like so ["Pending", "On Hold", "Done"]).

我将此方法添加到了枚举中.

I added this method to the enum.

func toArray() -> [String] {
    var n = 1
    return Array(
        GeneratorOf<EstimateItemStatus> {
            return EstimateItemStatus(id: n++)!.description
        }
    )
}

但是我遇到了以下错误.

But I'm getting the following error.

找不到类型为'GeneratorOf'的初始化程序，该初始化程序接受类型为((()-> _)')的参数列表

Cannot find an initializer for type 'GeneratorOf' that accepts an argument list of type '(() -> _)'

是否有更简单，更好或更优雅的方式来做到这一点?

Is there is an easier, better or more elegant way to do this?

推荐答案

对于Swift 4.2(Xcode 10)和更高版本

有一个CaseIterable协议:

enum EstimateItemStatus: String, CaseIterable {
    case pending = "Pending"
    case onHold = "OnHold"
    case done = "Done"

    init?(id : Int) {
        switch id {
        case 1: self = .pending
        case 2: self = .onHold
        case 3: self = .done
        default: return nil
        }
    }
}

for value in EstimateItemStatus.allCases {
    print(value)
}

---

对于Swift< 4.2

否，您无法查询enum包含的值.请参阅本文.您必须定义一个列出所有值的数组.另请在"如何获得所有枚举值作为数组.

---

For Swift < 4.2

No, you can't query an enum for what values it contains. See this article. You have to define an array that list all the values you have. Also check out Frank Valbuena's solution in "How to get all enum values as an array".

enum EstimateItemStatus: String {
    case Pending = "Pending"
    case OnHold = "OnHold"
    case Done = "Done"

    static let allValues = [Pending, OnHold, Done]

    init?(id : Int) {
        switch id {
        case 1:
            self = .Pending
        case 2:
            self = .OnHold
        case 3:
            self = .Done
        default:
            return nil
        }
    }
}

for value in EstimateItemStatus.allValues {
    print(value)
}

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