iOS Swift 3 - 提交后无法停止 UIActivityIndi​​catorView

Question

我有一个提交按钮，通过 HTTP 提交电子邮件和密码以进行验证在 JSON格式，但即使应用程序收到来自服务器的响应，指示器 View 也不会停止。

    @IBAction func signInButtonAction(_ sender: UIButton) {
    let validated = validateEmailAddressTextField()
    if validated {
        let emailAddress = emailAddressTextField.text
        let password = passwordField.text

        let url:URL = URL(string: "http://localhost:8080/app/user/signin")!
        let session = URLSession.shared

        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.allHTTPHeaderFields = ["Content-Type": "application/json"]
        request.cachePolicy = NSURLRequest.CachePolicy.reloadIgnoringCacheData

        let user = User(emailAddress: emailAddress!, password: password!)
        let requestJSON = careGiver.toJSON()

        request.httpBody = requestJSON?.data(using: String.Encoding.utf8)
        let indicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
        indicator.center = view.center
        view.addSubview(indicator)
        indicator.startAnimating()

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.0) {
            let task = session.dataTask(with: request as URLRequest) {
                (
                data, response, error) in

                guard let data = data, let _:URLResponse = response, error == nil else {
                    print("error")
                    return
                }
                let dataString =  String(data: data, encoding: String.Encoding.utf8)
                print(dataString)
                indicator.stopAnimating()
            }
            task.resume()
        }
    }
}

当我单击“提交”按钮时，我会在按钮顶部看到一个指示器 View ，但它不会停止并消失。

代码有什么问题吗？

我正在使用 Swift 3和 Xcode 8 .

谢谢。

Answer 1

indicator.stopAnimating()
尝试在主线程上运行这行代码:

DispatchQueue.main.async {
    indicator.stopAnimating()
}