labelに変化が起こりません。

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var cityTextField: UITextField!


    @IBOutlet weak var resultLabel: UILabel!
    @IBAction func findWeather(sender: AnyObject) {

        var wasSuccessful = false

        let attemptedUrl = NSURL(string: "http://www.weather-forecast.com/locations/" + cityTextField.text!.stringByReplacingOccurrencesOfString(" ", withString: "-") + "/forecasts/latest")!

        if let url:NSURL = attemptedUrl {

        let task = NSURLSession.sharedSession().dataTaskWithURL(url) { (data, response, error) -> Void in

            if let urlContent = data {

                let webContent = NSString(data: urlContent, encoding: NSUTF8StringEncoding)

                let websiteArray = webContent?.componentsSeparatedByString("3 Day Weather Forecast Summary:</b><span class=\"read-more-small\"><span class=\"read-more-content\"> <span class=\"phrase\">")

                if websiteArray!.count > 1 {

                    let weatherArray = websiteArray![1].componentsSeparatedByString("</span>")

                    if weatherArray.count > 1 {

                        wasSuccessful = true

                        let weatherSummary = weatherArray[0].stringByReplacingOccurrencesOfString("&deg;", withString: "º")

                        dispatch_async(dispatch_get_main_queue(), { () -> Void in


                            self.resultLabel.text = weatherSummary
                        })

                    }

                }



            }

            if wasSuccessful == false {

                **self.resultLabel.text = "Couldn't find the weather for that city - please try again."**

            }
        }

        task.resume()

        } else {

            **self.resultLabel.text = "Couldn't find the weather for that city - please try again."**

        }
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.


    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

天気予報アプリを作成しています。
** **で囲んだ欄に関してなのですが、都市名以外のことを入力された際には、** **で囲んだ内容をlabelに変換するようにしたつもりです。

しかし、都市名以外のことを入力してボタンを押しても、labelに変化が起きません。

これはコードのどこに問題があるのでしょうか？