[Swifty] File download memory management

Hi, We are seeing a similar issue when downloading files from Dropbox using Swifty Dropbox. The memory usage increases gradually to almost 2/3 of the file size by around 1 MB/sec. For example for a file of size 320 MB the memory usage goes from 40 MB (when download started) to 240 MB and stays there until the download is finished:

    let destination : (NSURL, NSHTTPURLResponse) -> NSURL = { temporaryURL, response in

        let localUrl = NSURL(fileURLWithPath: self.localPath)

        return localUrl

    }

    if let client = Dropbox.authorizedClient {

        client.files.download(path: dbPath, destination: destination).response

            {

                response, error in

                if let (metadata, url) = response {

                    if error != nil {

                        NSlog("Dropbox download failed. \(error!.description)", .Error)

                    }

                    else {

                        NSlog("Dropbox file downloaded.")

                    }

                }

        }

    }