Here’s another open source library created specifically for the purpose of concurrent multiple file downloading that does not use any networking framework (just NSURLConnection) and file downloading can be done with a single line of code.
This library provides a concurrent multiple data downloader with a blocks based syntax for callbacks. In addition the library provides download progress indicators, file caching, and download cancellation.
The library is BDMultiDownloader by Norsez Orankijanan and can be found on Github here.
A nice lightweight library for easy concurrent file downloading.