JSONDecoderがうまく行かない

override func viewDidLoad() {
        super.viewDidLoad()
        let listUrl = "http://hpscript.com/swift/index.php"
        do {
            guard let url = URL(string: listUrl) else { return }
            URLSession.shared.dataTask(with: url){(data, response, error) in
                if error != nil {
                    print(error!.localizedDescription)
                }
                
                guard let data = data else { return }
                let json = try? JSONDecoder().decode([JsonSample].self, from: data)
                }.resume()
            
        } catch{
            
        }
        self.label.text = json[0].name
        // Do any additional setup after loading the view, typically from a nib.
    }

なぜだ!!!!?