I am not receiving any data output?

private let apiKey = "6111785522cbc03124f6c419232df5fb"

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let baseURL = NSURL(string: "https://api.forecast.io/forecast/\(apiKey)/")
    let forecastURL = NSURL(string: "37.8267,-122.423", relativeToURL: baseURL)


    let sharedSession = NSURLSession.sharedSession()
    let downloadTask: NSURLSessionDownloadTask = sharedSession.downloadTaskWithURL(forecastURL!, completionHandler: { (location: NSURL!, response: NSURLResponse!, error: NSError!) -> Void in //dl data asynchoronously


        if (error == nil) {
            let dataObject = NSData(contentsOfURL: location)
            let weatherDictionary: NSDictionary = NSJSONSerialization.JSONObjectWithData(dataObject!, options: nil, error: nil) as NSDictionary //convert JSON data to NSDictionary


            let currentWeather = Current(weatherDictionary: weatherDictionary)
            println(currentWeather.temperature)

        }
        })
    downloadTask.resume()
}