枚举返回对象 (NSError)

Question

这个相对简单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)
    }
}

但是当试图从中提取时

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

它失败了，说：

AuthKitError is not convertible to NSError

如有任何想法，我们将不胜感激！谢谢你的时间。

Answer 1

error是枚举的一个实例属性，而AuthKitError.SignInFailedInvalidUsernamePassword是枚举的一个实例，所以你必须显式读取它的值：

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

枚举返回对象 (NSError)

Enum returning object (NSError)

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swift