Create a IPhone and android app

I would like an app where people can go to find people to play with for certain games. Video games weather it's Xbox or play station. Kind of like a forum but something a lil better. They need to make a user name to acces it and there they can add there gamer tag or username for there system. Kind of like an activity hub to show who is currently online and wants to play a certain game. Like a mixture of and activity hub and forums. If any questions message me. Skills needed probably Java and swift and others. Not very sure what else. And if you can help advertise that is also a plus.