I am using Starscream library for Websocket support. When i create socket i have this error.

func createConnection() {
     if let token = KeychainSwift().get(GlobalStrings.tokenKey),
        let url = URL(string: socketURLString + token) {
         let request = URLRequest(url: url)
         self.socket = WebSocket(request: request)
         self.socket?.callbackQueue = DispatchQueue(label: "Background",
                                               qos: .background,
                                               attributes: .concurrent,
                                               autoreleaseFrequency: .inherit, target: nil)
         self.socket?.delegate = self //error in this line always
         self.socket?.connect()
     }
 } 

In my other project with similar code - all good. Socket object is correct. Need a help. Thanks. PS. I use Starscream lib, and 1 lib that i use, use starscream too. It's problem. Can i do something to use lib and my code?