I'm currently showing a leaderboard in my game using Google Play Games. Now I want to add an "Invite" button in order to engage more users to the game, the idea is when you press the button, show a popup with all the friends in your circles, select one or more and then send the invites.
I've looked through the API but can't find anything. Weird thing is that this feature appears in the landing page of Google Play Services (https://developers.google.com/games/services/):
Help players ask friends to take specific action in a game, like "challenge", "attack", or "accept gift".
So maybe I'm missing something. Is this possible to do? How?
The invitations that you mention are for multiplayer games only. Whats the point of inviting to another person to a leaderboard?
Maybe what you want instead is to post the fact that you have unlocked an achievement, let's say on google+, for that I will sugest the following aproach:
https://developers.google.com/+/mobile/android/share/
Also, hold for the 4.1, I believe P2P wont be the only way to do multiplayer games and other stuff may be added too.