class BasicViewController: UIViewController {

    @IBOutlet weak var sampleTextView: UITextView!

    @IBOutlet weak var activityIndicator: UIActivityIndicatorView!

    override func viewDidLoad() {

        super.viewDidLoad()

        startSampleRequest()

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}

//------------------------------------------------------------------------------------

//                                     action setting

//------------------------------------------------------------------------------------

extension BasicViewController {

    func startSampleRequest() {

        guard let url = URL.init(string: "http://localhost:3001") else { return }

//        guard let url = URL.init(string: "https://www.baidu.com/") else { return }

        let session = URLSession.shared

        let task = session.dataTask(with: url) { (data, response, error) in

            if error != nil {

                print("error: \(String(describing: error))")

                return

            }

            guard let data = data else { return }

            DispatchQueue.main.async {

                sleep() // 为了测试效果, 暂停2秒

                let text = String.init(data: data, encoding: String.Encoding.utf8)

                self.toggleActivityIndicator(target: self.activityIndicator)

                self.sampleTextView.text = text

            }

        }

        task.resume()

    }

}

//------------------------------------------------------------------------------------

//                                     style setting

//------------------------------------------------------------------------------------

extension BasicViewController {

    private func toggleActivityIndicator(target: UIActivityIndicatorView) {

        if target.isAnimating {

            target.stopAnimating()

        } else {

            target.startAnimating()

        }

    }

}