Configure iOS GameCenter for iOS 7 and Unity3D using Prime31

How to Configure iOS GameCenter (GC) for iOS 7 and Unity3D using Prime31

Issue:

Since iOS 7 I no longer get the prompt from Game Center (GC) to ask me to log in sandbox mode when I open my application. I searched for a while and never saw any known issues about this and there are no patch notes that says anything about sandbox mode changing. Has anyone encountered this problem?

Work Around

This issue appears to happen in sandbox only.
Got this problem too, and here what we've find/figured out:
shows prompt for login only a few times (3-5), if all prompts were canceled - GC becomes disabled for this app. once its disabled for the app user can't enable GC for the app for setting.  so we have to just reset all setting of the device  through out, reseting Settings will reset WiFi Setting, iTune Accounts association.

Solution:

Step 1: Go to setting of Device and find GC and logout from GC if logged in
Step 2: Go to General - Find to Reset Option and choose Reset All Settings, Confirm it and wait till it restarted.
Step 3: if Updating first remove "GameCenter" folder from "Editor" and "Plugins" folder
Step 4: Imports GC latest package from prime[31]
Step 5: Update prime[31] tools from Prime[31] menu in unity (it will update few dlls in Editor and plugin folder)
Step 6: Delete Current XCode Build of game.
Step 7: Go to Build Settings and "Build" the game (not "Build and Run") it will run all pre-processors for GC settings
Step 8: Now go to device and sign out from GC (for iOS 5.x and 6.x GC App, for iOS 7 Settings==> (GC))
Step 9: Run your App and now you can test it...

If you are just updating your prime[31] plugin for gamecenter just start from step. For just update plugin version you have to remove all files from old plugin and build to fresh XCode from Unity using "Build Butoon" (not "Build and Run")

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