Unable to get variable right

Does anyone know how I can fix this?

the problem is that the prepareForSegue function is not getting the chanceRain variable. for some reason chanceRain only has a value inside the task variable. Does somebody know how to fix that? I tried to fix it in playground but I can't import SWXMLHash in it.

import UIKit
import SWXMLHash

class ViewController: UIViewController, UITableViewDelegate {

var cellContent = [""]
var indexOfTime = 0
var chanceRain = ""

@IBOutlet var cityInput: UITextField!

         func enumerate(indexer: XMLIndexer) {
         for child in indexer.children {
         NSLog(child.element!.name)
         enumerate(child)
       }
     }

@IBAction func button(sender: AnyObject) {

      var url = NSURL(string: "http://ift.tt/1IyBdaF?  key=ca89103dfe0a8b844a0a1e1249820&q=" +
      cityInput.text.stringByReplacingOccurrencesOfString(" ", withString: "-  ") + "/" + cityInput.text.stringByReplacingOccurrencesOfString(" ", withString: "- ") + "/" + "&num_of_days=2&tp=3&format=xml")

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

      var urlContent = NSString(data: data, encoding: NSUTF8StringEncoding)

      println(url)

var xml = SWXMLHash.parse(urlContent!)


  for elem in xml["data"]["weather"][0]["hourly"][self.indexOfTime]{
    self.chanceRain = (elem["chanceofrain"].element!.text!)

     }

     println(self.chanceRain)


   })
   task.resume()

 }

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {


      if(segue.identifier == "btnSubmitSegue"){


      var svc: viewTwo = segue.destinationViewController as viewTwo

      svc.datapassed = "hallo " + toString(chanceRain) //dit werkt, maar        chanceRain niet..?


  } }





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

         cellContent = ["01:00","04:00","07:00", "10:00", "13:00", "16:00", "19:00",    "22:00"]
  }

         func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

         return cellContent.count
}

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath:  NSIndexPath) -> UITableViewCell {

        let cell = UITableViewCell(style: UITableViewCellStyle.Default  ,  reuseIdentifier: "Cell")

        cell.textLabel?.text = "\(cellContent[indexPath.row])"

         return cell }

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath){

       indexOfTime = indexPath.row



 }



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