The bittorrent client for iOS is back from the dead and functional. Back in the day, if you wanted to download a torrent file on to your iOS device, you would use the jailbreak tweak iTransmission. But, as time passed, the developers stopped supporting the tweak and eventually it was no longer available for newer iOS devices and firmwares.
A jailbreak developer who goes by the name of iOShomebrew has restarted the iTransmission project and has made an alpha version available on the Cydia Store. iTransmission 2 is exactly the same as the first version and can be used to download torrents on to your iOS device. It works on iOS 5 and also on the latest iOS devices.
iTransmission 2 is still in alpha, so there may be certain bugs. This tweak is available for free in the BigBoss repo. Try it out and let us know if it worked for you.