JamesonQuave.com iOS 8 Swift Tutorial Part 6 cellForRowAtIndexPath

func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
        
        var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(kCellIdentifier) as UITableViewCell
        
        // Find this cell's album by passing in the indexPath.row to the subscript method for an array of type Album[]
        let album = self.albums[indexPath.row]
        cell.text = album.title
        cell.image = UIImage(named: "Blank52")
        cell.detailTextLabel.text = album.price
        
        dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
            // Jump in to a background thread to get the image for this item
            
            // Grab the artworkUrl60 key to get an image URL for the app's thumbnail
            //var urlString: NSString = rowData["artworkUrl60"] as NSString
            let urlString = album.thumbnailImageURL
            
            // Check our image cache for the existing key. This is just a dictionary of UIImages
            var image: UIImage? = self.imageCache[urlString!]

            if( !image? ) {
                // If the image does not exist, we need to download it
                let imgURL: NSURL = NSURL(string: urlString)
                
                // Download an NSData representation of the image at the URL
                let request: NSURLRequest = NSURLRequest(URL: imgURL)
                let urlConnection: NSURLConnection = NSURLConnection(request: request, delegate: self)
                NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue(), completionHandler: {(response: NSURLResponse!,data: NSData!,error: NSError!) -> Void in
                    if !error? {
                        image = UIImage(data: data)
                        
                        // Store the image in to our cache
                        self.imageCache[urlString!] = image
                        
                        // Sometimes this request takes a while, and it's possible that a cell could be re-used before the art is done loading.
                        // Let's explicitly call the cellForRowAtIndexPath method of our tableView to make sure the cell is not nil, and therefore still showing onscreen.
                        // While this method sounds a lot like the method we're in right now, it isn't.
                        // Ctrl+Click on the method name to see how it's defined, including the following comment:
                            /** // returns nil if cell is not visible or index path is out of range **/
                        if let albumArtsCell: UITableViewCell? = tableView.cellForRowAtIndexPath(indexPath) {
                            albumArtsCell!.image = image
                        }
                    }
                    else {
                        println("Error: \(error.localizedDescription)")
                    }
                })

            }
            else {
                cell.image = image
            }
            
            
        })
        return cell
    }