How to append JSON data into an array in swift

Hello Guys i need help I'm trying to save json data in an array but i'm not getting it properly can anyone help me here is the complete code

let url = URL(string: "http://localhost:3000/liveData/device/20042")
    URLSession.shared.dataTask(with: url!, completionHandler: {
        (data, response, error) in
        if(error != nil){
            print("error")
        }else{
            do{
                let json = try JSONSerialization.jsonObject(with: data!, options:[]) as! [[String: Any]]

                print(json)

                    for item in json {

                    if let title = item["BV"] as? String {
                        self.userIdArray.append(title)
                    }

                    if let title = item["BC"] as? String {
                        self.userIdArray.append(title)
                    }

                    if let title = item["SV"] as? String {
                        self.userIdArray.append(title)
                    }

                    if let title = item["SC"] as? String {
                        self.userIdArray.append(title)
                    }

                }

                DispatchQueue.main.async {
                    self.collectionView.reloadData()
                }

            }catch let error as NSError{
                print(error)
            }
        }
    }).resume()

I want to save json data in userIdArray can anyone help me, Thank you.

{
"SV" : 0,
"SC" : 0,
"BV" : 14.807,
"BC" : 0.024,
}

This is the output json