Swift 2 Function Call and JSON usage

I have a Problem with Swift and Xcode 7.

class ConnectVC: UITableViewController {

var username:Array< String > = Array < String >()

var TableData:Array< String > = Array < String >()

var pictures:Array< String > = Array < String >()

var profile_pictures:Array< String > = Array < String >()

override func viewDidLoad() {
    super.viewDidLoad()

    get_data_from_url("-url-")

}

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return TableData.count
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! ConnectVCCell

    let picture = pictures[indexPath.row]
    print(pictures.count)
    print(picture)
    print(profile_pictures.count)
    let pic = profile_pictures[indexPath.row]

    if picture != "" {
        let aString = "-url-"
        let url = NSURL(string: aString)
        let data = NSData(contentsOfURL: url!)
        print(url)
        let image = UIImage(data: data!)

        cell.imageURL.image = image
    }else{
        print("No picture")
        cell.imageURL.image = nil
    }

    cell.mainLabel.text = TableData[indexPath.row]
    return cell
}


func get_data_from_url(url:String)
{
    let url = NSURL(string: url)
    let urlRequest = NSMutableURLRequest(URL: url!,
        cachePolicy: .ReloadIgnoringLocalAndRemoteCacheData,
        timeoutInterval: 15.0)
    let queue = NSOperationQueue()
    NSURLConnection.sendAsynchronousRequest(
        urlRequest,
        queue: queue,
        completionHandler: {response, data, error in
            if data!.length > 0 && error == nil{
                let json = NSString(data: data!, encoding: NSASCIIStringEncoding)
                self.extract_json(json!)
            }else if data!.length == 0 && error == nil{
                print("Nothing was downloaded")
            } else if error != nil{
                print("Error happened = \(error)")
            }
        }
    )
}

func extract_json(data:NSString)
{

    let jsonData:NSData = data.dataUsingEncoding(NSASCIIStringEncoding)!

    do {
        // Try parsing some valid JSON
        let json: AnyObject? = try NSJSONSerialization.JSONObjectWithData(jsonData, options: .AllowFragments)

        let data_list = json as? NSArray

        for (var i = 0; i < data_list!.count ; i++ )
        {
            if let data_obj = data_list![i] as? NSDictionary
            {
                if let text = data_obj["text"] as? String
                {
                    if let picture = data_obj["picture"] as? String
                    {
                        if let user = data_obj["user"] as? String
                        {

                            self.save_image("-url-")

                            TableData.append(text + " [" + user + "]")
                            pictures.append(picture)
                        }
                    }
                }
            }
        }
    }
    catch let error as NSError {
        // Catch fires here, with an NSErrro being thrown from the JSONObjectWithData method
        print("A JSON parsing error occurred, here are the details:\n \(error)")
    }
    do_table_refresh();
}

func save_image(url:String){

    let url = NSURL(string: url)
    let urlRequest = NSMutableURLRequest(URL: url!,
        cachePolicy: .ReloadIgnoringLocalAndRemoteCacheData,
        timeoutInterval: 15.0)
    let queue = NSOperationQueue()
    NSURLConnection.sendAsynchronousRequest(
        urlRequest,
        queue: queue,
        completionHandler: {response, data, error in
            if data!.length > 0 && error == nil{
                let json = NSString(data: data!, encoding: NSASCIIStringEncoding)
                self.extract_json_picture(json!)
            }else if data!.length == 0 && error == nil{
                print("Nothing was downloaded")
            } else if error != nil{
                print("Error happened = \(error)")
            }
        }
    )
}
func extract_json_picture(data:NSString)
{
    let jsonData:NSData = data.dataUsingEncoding(NSASCIIStringEncoding)!

    do {
        // Try parsing some valid JSON
        let json: AnyObject? = try NSJSONSerialization.JSONObjectWithData(jsonData, options: .AllowFragments)

        print(json)

        let user_info = json as? NSArray

        if let user_list = user_info![0] as? NSDictionary
        {
            if let profile_picture = user_list["picture"] as? String
            {
                profile_pictures.append(profile_picture)
            }
        }

    }
    catch{

        print("A JSON parsing error occurred, here are the details:\n \(error)")

    }

With this Code I get the following Error:

fatal error: Array index out of range

in the following line:

let pic = profile_pictures[indexPath.row]

The Problem is, that the array is empty. But I don't see the Problem. I think the function where I fill the array is correctly called.

Can someone help?