Swift 2 php mysql注册问题

I'm fairly new to programming with Swift in Xcode so I have been recently following the fantastic php sql sign up tutorial by Sergey Kargopolov located here http://swiftdeveloperblog.com/store-user-information-in-mysql-database/.

Unfortunately the tutorial was slightly outdated and needed to be updated for Swift 2.0. I managed to substitute the problematic code by implementing a do/catch statement which seems to work great except when i receive a response from the server side php script I can't seem to navigate to different view controllers based on the result. For example if the response is "Registration Successful" the user is directed to the protected page however if the email address already exists in the database, I want it to stay on the same page.

Currently I have the code working to the point where the alert appears (either user already exists or successful) but when the user clicks "Ok", they are directed to the protected page regardless of the result. I figured it would be a simple case of telling it to go to the next view based on the result in this "if" statement:

    if (resultValue == "Success") {

    isUserRegistered = true 

    let next = self.storyboard?.instantiateViewControllerWithIdentifier("ProtectedViewController") as! ProtectedViewController
    self.presentViewController(next, animated: true, completion: nil)
    }

but it doesn't seem to work. Hopefully it makes sense what i'm trying to do and any help is greatly appreciated.

here is my code:

                let myUrl = NSURL(string: "http://localhost/PhpProject1/scripts/registerUser.php")
                let request = NSMutableURLRequest(URL: myUrl!)
                request.HTTPMethod = "POST"

                let postString = "userEmail=\(userEmail!)&userFirstName=\(userFirstName)&userLastName=\(userLastName)&userPassword=\(userPassword!)"

                request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding);

                let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {

                    data, response, error in

                    if error != nil {

                        print("error=\(error)")

                        return

                    }

                    do {

                        let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as? NSDictionary

                        if let parseJSON = json {

                            var resultValue = parseJSON["status"] as! String!

                            print("result: \(resultValue)")

                            var isUserRegistered: Bool = false


                            if (resultValue == "Success") {

                                isUserRegistered = true

                            }

                            var messageToDisplay: String = parseJSON["message"] as! String!

                            if (!isUserRegistered)

                            {

                                messageToDisplay = parseJSON["message"] as! String!

                            }

                            dispatch_async(dispatch_get_main_queue(), {

                                var myAlert = UIAlertController(title: "Alert", message: messageToDisplay, preferredStyle: UIAlertControllerStyle.Alert)

                                let okAction = UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default) { action in

//                            self.dismissViewControllerAnimated(true, completion: nil)
                                let next = self.storyboard?.instantiateViewControllerWithIdentifier("ProtectedViewController") as! ProtectedViewController
                                self.presentViewController(next, animated: true, completion: nil)

                                }

                                myAlert.addAction(okAction)

                                }

                            )}

                    } catch { print(error)}

                }

                task.resume()

            }

            func displayAlertMessage(userMessage:String) {

                let myAlert = UIAlertController(title: "Alert", message: userMessage, preferredStyle: UIAlertControllerStyle.Alert);

                let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil)

                myAlert.addAction(okAction);

                self.presentViewController(myAlert, animated: true, completion: nil)

            }
        }

I should also add that when the user registers successfully, I get "Result: 200" in the output window but when the user email already exists I get "Result: 400". I just don't know how to take advantage of this.

Thanks in advance!