Game Center achievements when not signed in to it

Question

I am building a game which uses achievements currently.

Let's imagine the following situation: The user starts the app the first time, does not sign in to GameCenter and gets a few achievements. But now he decides to use GameCenter and signs in some time later. What happens to the gained achievements? Will they be sent to the GameCenter servers later on or do I need to program a check-for-gained-achievements method manually? What did you do?

Thanks for your help!

Answer 1

I stored the data locally in a plist and submit when they login.

Answer 2

In iOS 5 or newer iOS, you have another option to submit offline the achievements and scores when users are not logon to Game Center. This utility behaves as a local cache when users are offline, and it will submit the achievements and scores to Game Center next time the gamers logon to Game Center.

Here is the link a similar question to yours and the answer:

Offline Game Center iOS Achievements

Cheers.