Quave's Swift tutorial thumbnail glitch fix

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

        var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(kCellIdentifier) as UITableViewCell
        if cell == nil {
            cell = UITableViewCell(style: UITableViewCellStyle.Subtitle, reuseIdentifier: kCellIdentifier)
        }

        var rowData: NSDictionary = self.tableData[indexPath.row] as NSDictionary

        // Add a check to make sure this exists
        let cellText: String? = rowData["trackName"] as? String
        cell.text = cellText

        var urlString: NSString = rowData["artworkUrl60"] as NSString
        var image: UIImage? = self.imageCache.valueForKey(urlString) as? UIImage
        if (!image?) {
            cell.image = UIImage(named: "Blank52")
            dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {

                // If the image does not exist, we need to download it
                var imgURL: NSURL = NSURL(string: urlString)

                // Download an NSData representation of the image at the URL
                var request: NSURLRequest = NSURLRequest(URL: imgURL)
                var urlConnection: NSURLConnection = NSURLConnection(request: request, delegate: self)
                NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue(), completionHandler: {(response: NSURLResponse!,data: NSData!,error: NSError!) -> Void in
                    if !error? {
                        //var imgData: NSData = NSData(contentsOfURL: imgURL)
                        image = UIImage(data: data)

                        // Store the image in to our cache
                        self.imageCache.setValue(image, forKey: urlString)
                        cell.image = image
                    }
                    else {
                        println("Error: \(error.localizedDescription)")
                    }
                    })
                })

        } else {
            cell.image = image!
        }



        // Get the formatted price string for display in the subtitle
        var formattedPrice: NSString = rowData["formattedPrice"] as NSString

        cell.detailTextLabel.text = formattedPrice

        return cell
    }