I’m looking to this but I can’t find anything related on connecting with Facebook and others, I’ve read people saying that we need to do this with C++ and such but it sounds like you need to guess all that without any info about it.
So, any of you guys got this on your app??
Firstly … what do you want to do with Facebook and Twitter?
If you can explain that, than maybe we can try to help you. I have integrated Twitter to my game that posts a Tweet on the games main Twitter Timeline with a mention using the player’s Twitter handle indicating they are joining a game or hosting a game. I used a restful call from the game to a restful web-service running off my Game Flow system to achieve this.
Just share scores in the game with other people. I’m playing the game called “Dungeons&Burglar” made with UE4 and it has this possibility into the game.
I’m interested in connecting with Facebook too.
Use Facebook as the user account, find friends who also play this game, share/show score, send gift, etc.
It would be useful for mobile games.
I can resolve your problem! I’ve just released plugin with Facebook implementation for iOS & Android! 
More info:
Patryk,
gameDNA studio
Or you can use the UMG browser widget along with the VaRest plugin. (for free)
Yep but in this case you don’t have native experience. The biggest advantage of this plugin is native iOS & Android implementation.