This isn’t exactly using iOS, but as you asked for a workaround, I’ll chime in. I use my server at home. I can find the torrents using the iPad, load them onto my server, torrent them there, and then use them on my iPad.
Now I have a DSM, but anything at all that you can remote into will work obviously, even a 35 quid rPi. Using a pi even makes it portable.
It’s not exactly torrenting with my iPad as I said. Works a treat though.