Get index of enum with extension of String,

Question

I have an Enum that looks like this:

enum Status: String {
    case online = "online"
    case offline = "offline"
    case na = "na"
}

I need the String value and I know how to get it, but my question is if it´s possible to get the index value too for each case in the enum.

0 for online, 1 for offline and 2 for na.

I will add more statues in the future.

Answer 1

-------- UPDATE -------

Since swift 4.2 you can do following:

enum Status: String, CaseIterable {

    case online
    case offline
    case na
}

extension CaseIterable where Self: Equatable {

    var index: Self.AllCases.Index? {
        return Self.allCases.index { self == $0 }
    }
}

or as I wrote earlier:

enum Status: Int {

    case online = 0
    case offline
    case na

    var index: Int {
        return rawValue
    }
    var value: String {
        return String(describing: self)
    }
}

-------- ORIGIN ANSWER -------

I'm using this extension:

protocol EnumIterable: RawRepresentable {

    static var allValues: [Self] { get }
    var index: Int? { get }
}

extension EnumIterable {

    static var count: Int {
        return allValues.count
    }
}

extension EnumIterable where Self.RawValue: Equatable {

    var next: Self? {
        if let index = Self.allValues.index(where: { rawValue == $0.rawValue }) {
            return Self.allValues[safe: index + 1]
        }
        return nil
    }

    var index: Int? {
        return Self.allValues.index { rawValue == $0.rawValue }
    }
}

But you would define allValues variable:

enum Status: String, EnumIterable {

    case online = "online"
    case offline = "offline"
    case na = "na"

    static var allValues: [Status] {
        return [
            .online,
            .offline,
            .na,
        ]
    }
}

Something similar was solved here (count of enumerations): How do I get the count of a Swift enum?

Next possibility is to define enum like this:

enum Status: Int {

    case online = 0
    case offline
    case na

    var index: Int {
        return rawValue
    }
    var value: String {
        return String(describing: self)
    }
}

print (Status.online.value) // online
print (Status.online.index) // 0

or

enum Status: Int {

    case online = 0
    case offline
    case na

    var index: Int {
        return rawValue
    }
    var value: String {
        switch self {
        case .online:
            return "online"
        case .offline:
            return "offline"
        case .na:
            return "na"
        }
    }
}

print (Status.online.value) // online
print (Status.online.index) // 0

Note: for defining string value, you can use CustomStringConvertible protocol.

Eg:

enum Status: Int, CustomStringConvertible {

    case online = 0
    case offline
    case na

    var index: Int {
        return rawValue
    }
    var description: String {
        switch self {
        case .online:
            return "online"
        case .offline:
            return "offline"
        case .na:
            return "na"
        }
    }
}

Answer 2

As enum in Swift does not have index of its values (please read the post in Martin R's comment), you have to create your self some 'index' function or to map all values to an Array to have the index.

You can implement as in this post or another way to do:

enum Status: String {
    case online = "online"
    case offline = "offline"
    case na = "na"

    static func index(of aStatus: Status) -> Int {
        let elements = [Status.online, Status.offline, Status.na]

        return elements.index(of: aStatus)!
    }

    static func element(at index: Int) -> Status? {
        let elements = [Status.online, Status.offline, Status.na]

        if index >= 0 && index < elements.count {
            return elements[index]
        } else {
            return nil
        }
    }
}

let a = Status.na

//return 2
let index = Status.index(of: a)

//return Status.offline
let element2 = Status.element(at: 1)

//return nil
let element3 = Status.element(at: 3)