Swift UIAlert - 从 dataTaskWithRequest 获取数据

Question

我需要从“dataTaskWithRequest”中获取变量“response”。现在，找不到“response”，因为它在括号之外。我怎样才能确保将响应变量传递给 UIAlert？谢谢

这是我的代码:

@IBAction func buttonCreateAccount(sender: AnyObject) {
            let request = NSMutableURLRequest(URL: NSURL(string: "http://www.example.com/createaccount.php")!)
            request.HTTPMethod = "POST"
            let postString = "user_name=\(username.text!)&email=\(email.text!)&password=\(password.text!)"
            request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

            let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
                data, response, error in

                if error != nil {
                    print("error=\(error)")
                    return
                }

                print("response = \(response)")

                let response = String(data: data!, encoding: NSUTF8StringEncoding)
                print("responseString = \(response)")

            }

            task.resume()

//problem is here. 'response' variable cannot be taken from above. i need it to be taken from above.
            if response == "Username taken" {
                if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8
                    let myAlert: UIAlertController = UIAlertController(title: "Registration", message: response, preferredStyle: .Alert)
                    myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
                    self.presentViewController(myAlert, animated: true, completion: nil)
                } else { // iOS 7
                    let alert: UIAlertView = UIAlertView()
                    alert.delegate = self

                    alert.title = "Registration"
                    alert.message = "Testing"
                    alert.addButtonWithTitle("OK")

                    alert.show()
                }
            } else {
                if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8
                    let myAlert: UIAlertController = UIAlertController(title: "Registration", message: response, preferredStyle: .Alert)
                    myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
                    self.presentViewController(myAlert, animated: true, completion: nil)
                } else { // iOS 7
                    let alert: UIAlertView = UIAlertView()
                    alert.delegate = self

                    alert.title = "Registration"
                    alert.message = "Testing"
                    alert.addButtonWithTitle("OK")

                    alert.show()
                    self.dismissViewControllerAnimated(true, completion: {});
                }
            }
        }

Answer 1

dataTaskWithRequest 运行异步。您不会立即收到回复。将它分成两个函数:

@IBAction func buttonCreateAccount(sender: AnyObject) {
    let request = NSMutableURLRequest(URL: NSURL(string: "http://www.example.com/createaccount.php")!)
    request.HTTPMethod = "POST"
    let postString = "user_name=\(username.text!)&email=\(email.text!)&password=\(password.text!)"
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in

        if error != nil {
            print("error=\(error)")
            return
        }

        print("response = \(response)")

        let response = String(data: data!, encoding: NSUTF8StringEncoding)
        print("responseString = \(response)")

        // Now that the response is ready, call the other function to handle it
        handleResponse(response)
    }

    task.resume()
}

func handleResponse(response: String) {
    if response == "Username taken" {
        if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8
            let myAlert: UIAlertController = UIAlertController(title: "Registration", message: response, preferredStyle: .Alert)
            myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
            self.presentViewController(myAlert, animated: true, completion: nil)
        } else { // iOS 7
            let alert: UIAlertView = UIAlertView()
            alert.delegate = self

            alert.title = "Registration"
            alert.message = "Testing"
            alert.addButtonWithTitle("OK")

            alert.show()
        }
    } else {
        if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8
            let myAlert: UIAlertController = UIAlertController(title: "Registration", message: response, preferredStyle: .Alert)
            myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
            self.presentViewController(myAlert, animated: true, completion: nil)
        } else { // iOS 7
            let alert: UIAlertView = UIAlertView()
            alert.delegate = self

            alert.title = "Registration"
            alert.message = "Testing"
            alert.addButtonWithTitle("OK")

            alert.show()
            self.dismissViewControllerAnimated(true, completion: {});
        }
    }
}