And if you're considering #Shoyu ( #iOS app ) as your #GNU_Social client, it is garbage. It apparently was an old Twitter client that supports Twitter's functionality from several years ago, and very little else. It is slooo-o-o-o-o-o-owwwww to post, even when other clients are not.
I haven't seen anything else for iOS that supports GS, but it might be worth going to the big blue discount store (aka #Walmart ) and buying their $80 #Android device, so you can use #AndStatus instead. AndStatus is not known for being fast, but it can run circles around Shoyu, even running backwards, with its eyes closed and its ankles bound.