I’ve been working on making an Ad Free version of my Candy Bubble Drop game and decided to use the GameCenter grouped Leaderboards & Achievements so both versions will share them.

This is pretty simple to setup in iTunesConnect, however (and why would I expect anything different) I ran into an issue with the way I had my Leaderboards & Achievements setup.

For the free version, I’d used ‘.Zone1’ as a Leaderboard ID and ‘.Zone1’ as an achievement ID.  The Leaderboard is used to record the best scores from Zone1 and the achievement is set when the player completes all the levels in Zone1.  Even though they have exactly the same ID, this never caused a problem, and I think I’ve done something like this in other Apps.

When I came to make a GameCenter Group, it updates all the IDs by prefixing them with ‘grp.’ and it wouldn’t accept that a Leaderboard and an Achievement have the same ID.  I modified the group achievement IDs, but now I need to code up a hack to modify the ID I submit to match the one I entered in GameCenter.

Morale of the story — DON’T use the same identifier for Leaderboards & Achievements in GameCenter, it might work just fine, but if you ever decide to group it with another App, then you’ll have to end up hacking your code to allow for a different ID.