具有符合CaseIterable、RawRepresentable的关联值的枚举

我正在尝试使具有关联值的枚举符合casiterable和rawrepresentable。当使用rawvalue初始化时,我可以使用一些关联值的默认值。

enum GenresAssociated: CaseIterable, RawRepresentable, Equatable {
    case unknown(String)
    case blues(String)
    case classical(String)
    // Implementing CaseIterable
    typealias AllCases = [GenresAssociated]
    // Enums can have no storage, but the class they are in CAN. Note 'static' in declaration
    static var allCases: [GenresAssociated] = [.unknown(""), .blues(""), .classical("")]


    typealias RawValue = Int
    var rawValue: Int {

        // MARK: This causes a crash for unknown reason
        return GenresAssociated.allCases.firstIndex(where: {  if case self = $0 { return true } else { return false } } ) ?? 0
    }
    init?(rawValue: Int) {
        guard GenresAssociated.allCases.indices.contains(rawValue) else { return nil }
        self = GenresAssociated.allCases[rawValue]
    }
}

是否有任何方法可以在所有情况下不手动切换,即没有这样的代码:

    typealias RawValue = Int
    var rawValue: Int {
        switch self {
        case .unknown:
            return 0
        case .blues:
            return 1
        case .classical:
            return 2
        }
    }

值得注意的是,非常相似的代码工作得很好,例如

enum EnumWithValue {
    case one(NSString!), two(NSString!), three(NSString!)
}

let arrayOfEnumsWithValues: [EnumWithValue] = [.one(nil), .two(nil), .three("Hey")]

if let index = arrayOfEnumsWithValues.firstIndex(where: { if case .two = $0 { return true }; return false }) {
    print(".two found at index \(index)") //prints ".two found at index 1"
}