切换Swift - 交换机中的案例标签应至少有一个可执行语句 [英] Switch in Swift - Case label in a switch should have at least one executable statement

问题描述

我有一个枚举类型，在Swift中扩展 String 。

I have an enum type that extends String in Swift.

当我尝试使用开关时，我发现错误：

When I try to use a switch I got an error:

交换机中的案例标签应至少有一个可执行语句

Case label in a switch should have at least one executable statement

这是我的代码：

enum UserInfosKey:String {
   case CameraMyPhotoStream = "CMPS"
    case CameraICloudActivated = "CICA"
    case CameraICloudShare = "CICS"
    case ProjectTodayExtension = "PTE"
    case ProjectShareExtension = "PSE"
    case NetworkConnection = "NC"
    case PhoneLanguage = "PL"
    case CameraPhotosCount = "CPC"
    case UserIdentifier = "UI"
    case VersionHistory = "VH"
    case Path = "Path"

}

class UserInfosController: NSObject {
    func update(key:UserInfosKey, value:String, context:UserDefaultsMainKeys) -> String {
        switch key {
        case .CameraICloudActivated:
        case .CameraICloudShare:
        case .CameraMyPhotoStream:
        case .CameraPhotosCount:
        case .NetworkConnection:
        case .PhoneLanguage:
        case .UserIdentifier:
            return value

        default:
            return ""
        }
    }
}

我很确定这是一个简单的错误，有人看到吗？

I'm pretty sure it's a simple mistake, anyone see it?

推荐答案

在快速开关语句中没有隐含的突破，所以你必须明确地设置： p>

There is no implicit fallthrough in the swift switch statement, so you have to explicitly set that:

    case .CameraICloudActivated: fallthrough
    case .CameraICloudShare: fallthrough
    case .CameraMyPhotoStream: fallthrough
    case .CameraPhotosCount: fallthrough
    case .NetworkConnection: fallthrough
    case .PhoneLanguage: fallthrough
    case .UserIdentifier:
        return value

没有这种情况，每个案例都有隐式中断。

Without that, each case has implicit break.

请注意，swift要求每个交换机案例至少包含一条语句 - 如果没有语句必须使用明确的 break （在这种情况下，这意味着do nothing）

Note that swift requires that each switch case contains at least one statement - in case of no statement, an explicit break must be used (which in this case means "do nothing")

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