Swift 3 升级 : Type 'Dictionary<NSObject, AnyObject>?' has no subscript members

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

它出现的函数如下:

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
}

我在“current SSID =”行收到错误。这段代码在 Swift 2.3 中运行良好，不幸的是，我不擅长标记为“不安全”的东西，所以如果答案深入到那些区域，那么如果你能尽可能简单地解释它会很有帮助。

感谢阅读!

Answer 1

改变

let interfaceData = unsafeInterfaceData! as Dictionary!

到

let interfaceData = unsafeInterfaceData! as NSDictionary

原因:unsafeInterfaceData 是一个 CFDictionary。 CFDictionary 可直接转换为 NSDictionary，因为它们是免费桥接的。这足以让我们订阅，因此我们可以使用像 interfaceData["SSID"] 这样的表达式。