Question

我最近将我的应用程序从Swift 2.3升级到Swift 3.0，当我这样做时，我收到以下错误：

Type 'Dictionary<NSObject, AnyObject>?' has no subscript members

出现的功能如下：

class func getSSIDConnectionName() -> String? {
    var currentSSID: String?
    let interfaces = CNCopySupportedInterfaces()
    if interfaces == nil {
        print("Got nil up here")
        return nil
    }

    let interfaces2:CFArray! = interfaces
    for i in 0..<CFArrayGetCount(interfaces2) {
        let interfaceName: UnsafeRawPointer = CFArrayGetValueAtIndex(interfaces2, i)
        let rec = unsafeBitCast(interfaceName, to: AnyObject.self)
        let unsafeInterfaceData = CNCopyCurrentNetworkInfo("\(rec)" as CFString)
        if unsafeInterfaceData != nil {
            let interfaceData = unsafeInterfaceData! as Dictionary!
            currentSSID = interfaceData["SSID"] as? String
        } else {
            print("Got nil down here")
            return nil
        }
    }

return currentSSID
}

我收到“当前SSID =”行的错误。这段代码在Swift 2.3中工作得很好，不幸的是，我对标记为“不安全”的东西并不强烈，所以如果答案深入研究这些区域，那么如果你能尽可能简单地解释它，那将是最有帮助的。

感谢阅读！

Answer 1

更改

let interfaceData = unsafeInterfaceData! as Dictionary!

到

let interfaceData = unsafeInterfaceData! as NSDictionary

原因：unsafeInterfaceData是CFDictionary。 CFDictionary可以直接转换为NSDictionary，因为它们是免费桥接的。这足以让我们订阅，所以我们可以使用像interfaceData["SSID"]这样的表达式。

Answer 2

除了@matt所说的，你的代码可以大大简化，特别是通过将返回值从CNCopySupportedInterfaces()转换为Swift [String]数组，和可选的绑定if let而不是针对nil进行测试并强行打开：

func getSSIDConnectionName() -> String? {

    guard let interfaces = CNCopySupportedInterfaces() as? [String] else {
        return nil
    }
    for ifname in interfaces {
        if let interfaceData = CNCopyCurrentNetworkInfo(ifname as CFString) as? [String: Any],
            let currentSSID = interfaceData["SSID"] as? String {
            return currentSSID
        }
    }
    return nil
}

Answer 3

键或下标的数据类型需要“NSObject”。 SWIFT 3似乎强迫您将其转换为正确的数据类型。如果你有

currentSSID = interfaceData?[String("SSID") as NSObject] as? String

或

currentSSID = interfaceData?["SSID" as NSObject] as? String

汇编将消失。只是要注意其他人的答案也可以。

Swift 3升级：输入'Dictionary <nsobject，anyobject =“”>？'没有下标成员

3 个答案: