URLSession
open override fun URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL: NSURL)
open override fun URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError: NSError?)
open override fun URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData: Long, totalBytesWritten: Long, totalBytesExpectedToWrite: Long)