无法下标'[NSObject：AnyObject]类型的值？” 索引类型为'String'的Swift错误

Question

My cod is that one and this error appears in the last line of the class, what should I do to solve it?

public class SSID {
            class func fetchSSIDInfo() -> String {
                var currentSSID = ""
                if let interfaces = CNCopySupportedInterfaces() {
                    for i in 0..<CFArrayGetCount(interfaces) {
                        let interfaceName: UnsafeRawPointer = CFArrayGetValueAtIndex(interfaces, 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
                        }
                    }
                }
                return currentSSID
            }
        }

Answer 1

The only lines that uses a subscript are:

let interfaceData = unsafeInterfaceData! as Dictionary!
currentSSID = interfaceData?["SSID"] as String

Accessing with a string like this: interfaceData?["SSID"] requires you to define your dictionary differently, your current dictionary is declared as [NSObject: AnyObject] but to use a String subscript it would need to be [String: AnyObject]

Try changing this line to:

let interfaceData = unsafeInterfaceData! as [String: AnyObject]

Note: Best to use if let rather than force unwrapping with !

Answer 2

You can try

if  let interfaceData = unsafeInterfaceData! as? [String:Any]
{
    currentSSID = interfaceData["SSID"] as? String
}