GameKit provides features you can use to create great social games. Games can post scores and achievements, display leaderboards, add friends, discover new games, and more.
Don’t design a custom sign-in screen. People are automatically prompted to sign into GameKit-enabled games if they’re not already signed in on their device. Displaying a custom sign-in screen is repetitive and can be confusing to people who are expecting the standard one.
In general, use standard GameKit interfaces. In rare cases, it might make sense for a game to include a custom version of a GameKit-provided screen, but doing so risks confusing people. The standard GameKit screens are designed to provide a familiar experience to a large gaming community across all Apple platforms.
Let people turn off voice chat. Some people might not want voice chat to be on automatically when they start your game, and everyone appreciates the ability to turn off voice chat in certain situations.
For implementation details, see GameKit.