ImageCaching for CellForRow

code1.swift

let id = thought.valueForKey("id") as! String

if let cachedImage = ImageCache.sharedCache.imageForKey("image-\(id)") {
    cell.picture.image = cachedImage
} else {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
        
        let scaledImage = Helper.scaleUIImageToSize(image!, size: size)
        ImageCache.sharedCache.setImage(scaledImage, forKey: "image-\(id)")
        dispatch_async(dispatch_get_main_queue(), {
            cell.picture.image = scaledImage
        })
        
    })
}