Play Games With Friends
Invite
friends to a multiplayer game. Tap Friends, choose a friend, choose
a game, then tap 
in
the upper
right. If the game allows or requires additional players, choose
the players to invite, then tap Next. Send your invitation, then
wait for the others to accept. When everyone is ready, start the
game. If a friend isn't available or doesn't respond to your
invitation, you can tap Auto-Match to have Game Center find another
player for you, to tap Invite Friend to invite someone
else.
Send a friend request. Tap Friends, tap
then enter
your friend's email address or Game Center nickname. To browse your
contacts, tap 
.
(To add several friends with one request, type Return after each
address.) Or, tap any player you see anywhere in Game
Center.
Challenge someone to outdo you. Tap one of your scores or achievements, then tap Challenge Friends.
What are your friends playing and how are they doing? Tap Friends, tap your friend's name, then tap the Games or Points bubble.
Want to purchase a game your friend has? Tap
Friends, then tap your friend's name. Tap their Games bubble, tap
the game in the list, then tap 
in the
upper right.
Make new friends. To see a list of your friend's friends, tap Friends, tap your friend's name, then tap their Friends bubble.
Unfriend a friend. Tap Friends, tap the
friend's name, then tap 
in the
upper right.
Keep your email address private. Turn off Public Profile in your Game Center account settings. See "Game Center settings" below.
Turn off multiplayer activity or friend requests. Go to Settings > General > Restrictions and turn off Multiplayer Games or Adding Friends. If the switches are grayed, tap Enable Restrictions at the top first.
Keep it friendly. To report offensive or inappropriate behavior,
tap Friends, tap the person's name, tap 
in the
upper right, then tap Report a Problem.