Have you tried https://siskin.im/ ? I’ve seen some people reporting success but (as I don’t have an iOS device) I haven’t tested this personally.
@wiktor Thanks for the suggestion! Siskin seems very promising as a lightweight and more actively developed alternative to ChatSecure, but OMEMO only functioned in one-to-one chats.
@wiktor Yes, currently OMEMO is only supported for 1-to-1 chats. MUC omemo is on our roadmap, but we don't have currently any ETA.
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!