Ios 如何在swift中比较枚举？

在Objective-C中，这很好

无法在Swift中编译此文件

或

IOS SDK中的授权状态定义

enum ALAuthorizationStatus : Int {
    case NotDetermined // User has not yet made a choice with regards to this application
    case Restricted // This application is not authorized to access photo data.
    // The user cannot change this application’s status, possibly due to active restrictions
    //  such as parental controls being in place.
    case Denied // User has explicitly denied this application access to photos data.
    case Authorized // User has authorized this application to access photos data.
}

---

比较运算符

==

返回一个

Bool

，而不是

Boolean

。 汇编如下：

func isAuthorized() -> Bool {
    let status = ALAssetsLibrary.authorizationStatus()
    return status == ALAuthorizationStatus.Authorized
}

（就我个人而言，我发现来自Swift编译器的错误消息有时令人困惑。 在本例中，问题不是

==

的参数，而是返回类型不正确。）

---

实际上，由于自动类型推断，还应编译以下内容：

但它失败，编译器错误为“找不到成员‘授权’”，除非您 明确指定

status

变量的类型：

func isAuthorized() -> Bool {
    let status:ALAuthorizationStatus = ALAssetsLibrary.authorizationStatus()
    return status == .Authorized
}

这可能是当前Swift编译器中的一个bug（使用Xcode 6 beta 1测试）

---

更新：第一个版本现在在Xcode 6.1中编译。

请向我们展示IOS SDK中的enum definition.AssetsLibrary

func isAuthorized() -> Bool {
    let status:ALAuthorizationStatus = ALAssetsLibrary.authorizationStatus()
    return status == .Authorized
}