You are probably familiar with achievement notifications that popup when you are playing games on a console system such as the Xbox 360.
The developers at t1e Studios have come up with a neat little library that allows you to generate these notifications with a styling that makes them fit perfectly with Game Center known as GKAchievementNotification.
In the screenshot you see the Game Center symbol, which potentially could get your app rejected as this is not part of the official game center API, but you can easily change the image or remove it altogether.
For more details on the implementation check out t1e Studio’s post on the usage of GKAchievementNotification:
You can find the Github repository here:
[via Alex Curylo]