Xcode changed and Apple has made our lives all the more difficult. They have even removed all site references to XCode 4 and iOS 6. So we can't see the documentation or help pages associated with them.
If you aren't using the v108 betas, then you probably have v1076, the 'official' release. I don't recognize 'v1.78'.
Until someone at TGC tries to work with this, we are stuck and need to stick with Xcode 4 to build AppGameKit apps.
And I suspect that Xcode 4 won't talk to an iOS 7 device.
And, once you have updated to iOS 7, you are stuck with it. Apple won't let you downgrade back to iOS 6 once you have passed the 'grace period'. I think that is only a few days. And downgrading appears to be related to having a jail broken iDevice before you upgraded.
Which is why I have not allowed any of the iOS devices I have access to (mine and my husbands) that are used for testing to update to iOS 7.
I am currently reading an article about iOS 7 making people sick. Something along the lines of sea sickness.
Nope, I don't plan to update until absolutely forced to and TGC has AppGameKit projects that will build in Xcode 5.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master