swift - 枚举返回对象(NSError)

Question

这个相对简单的enum，编译得很好，但是......

public protocol AuthKitErrorProtocol {
    var error: NSError { get }
}

enum AuthKitError: AuthKitErrorProtocol {
    case SignInFailedInvalidUsernamePassword
    case SignInFailedInvalidSecondFactor

    var error: NSError {
        let (codeK: Int,
        userInfoK: Dictionary<String, String>
        ) = {
            switch self {
            case .SignInFailedInvalidUsernamePassword:
                return (1000,
                    [ NSLocalizedDescriptionKey: "Operation failed.",
                        NSLocalizedFailureReasonErrorKey: "Invalid usename or password",
                        NSLocalizedRecoverySuggestionErrorKey: "Please try again" ]
                )

            case .SignInFailedInvalidSecondFactor:
                return (1001,
                    [ NSLocalizedDescriptionKey: "Operation failed.",
                        NSLocalizedFailureReasonErrorKey: "Invalid second factor code",
                        NSLocalizedRecoverySuggestionErrorKey: "Please try again" ]
                )

            default:
                return (-999,
                    [ NSLocalizedDescriptionKey: "Operation failed.",
                        NSLocalizedFailureReasonErrorKey: "Unknown reason",
                        NSLocalizedRecoverySuggestionErrorKey: "Please call customer support" ]
                )

            }
            }()

            return NSError(domain: kAuthKitErrorDomain, code: codeK, userInfo: userInfoK)
    }
}

但是当尝试从中提取时

var err: NSError  = AuthKitError.SignInFailedInvalidUsernamePassword
println("error is : \(err)")

它失败了，说:

AuthKitError is not convertible to NSError

任何想法将不胜感激!感谢您抽出时间。

Answer 1

error 是枚举的实例属性，AuthKitError.SignInFailedInvalidUsernamePassword 是枚举的实例，因此您必须显式读取其值:

var err: NSError  = AuthKitError.SignInFailedInvalidUsernamePassword.error
                                                                    ^^^^^^