I want my app to create a new Facebook group chat with certain people that opens either on Facebook's site in Safari or in the native Facebook app when the user presses a button. I want Facebook to handle the whole chat and my app only to initiate it somehow in the cleanest and least involved way possible. My app already uses the Facebook SDK to open an active FBSession, so I've already got login credentials.
Looking around online and in Facebook's docs, I can't find anything that suits my needs. The closest thing I found was in this answer containing a list of Facebook app URLs you can connect to that open the Facebook app to certain pages. There's "fb://chat/(initWithUID:)" and "fb://messaging/compose/(initWithUID:)". However, not only is there no explanation on how to use these, but people say that Facebook has changed these URLs (and does not have any documentation on them), so they don't work anymore unless I reverse-engineer new URLs (which could change again). Ugh, so close!
I also found examples on starting chats with the Facebook Chat API, but that involves logging into Facebook using some networking framework then writing my own GUI and model for sending messages, which I am only prepared to do as a last resort. There should be some way to let the Facebook app or website do all that. Does anyone know how I can do this?