Sport group creating app

We need an app developer who will create an android and apple compatible app what can use for creating small teams (2, 4, 8, 16 players), especially send invitation (push notification) to selected players and they can join or not join to the game and when game is full close the game and invitations. Background. In our sport, we always need 4 players to play the game like in beach volleyball. We have a limited number of courts and a limited number of times (specially prime times) for the courts. We want an app that makes it easy to create 4 people groups using he’s contact lists what user need to create, example from her own phone book contact list or manually. Now we use WhatsApp, which is not the best. Request Logging - Log in to gmail, facebook, etc - Phone number required and text message verification - Possible to import contacts (example phonebook) - My Information tab, basic staff name, email etc… Elements - Create own contact groups (Private) - Share own groups of contacts (Public) - Edit own group, add and remove people in the list - Use public groups - Create gamen invitation and send notification all players - Show who is seeing invitation, who answer yes, no, maybe - Basic chat between individual players where players can ask something about that game, or tell why he gant join that game Create an game invitation (main thing) - General information such as: time, place, price, description - How many players are called 2,4,8,12… - Invite players (check box from contact list) or your groups - Latest register/answer time (deadline), after that game ”die” if we can’t get all players Push notification (email mayby) to anyone who is invited that game. Who accept invitation first get place to game. LISTINGS Inbox tab - See where you've been invited - Answer the call yes, no, maybe - If you answer yes, then one place will be deducted from the game - Notify the caller with a push notification that he has answered - Before agreed games tab - See what you are participating in Games history tab - See what you've been involved in