Bad Access Challenges

Question

When a user's friend challenges his highscore, and the user beats it, it replies with a new challenge (By apple, not programmed). The other user gets the challenge, but the sender's game immediately crashes with Bad Access on this line if ([_delegate respondsToSelector:@selector(onScoresSubmitted:)]) from this tutorial http://www.raywenderlich.com/23189/whats-new-with-game-center-in-ios-6

Any ideas?

Answer 1

Are you sure that your _delegate is not random garbage value at this point?.

if ([_delegate respondsToSelector:@selector(onScoresSubmitted:)])

Make sure the client (delegate) who use the callBack clean the server delegate so that the callBack is not done anymore.

This can be done in two way:

1. A: make from the sever side a retain of the delegate (but it's not a delegate relationship anymore).
2. B: assign to nil the delegate pointer when the delegate client doesn't need the service anymore.

Here a common error, because of a bad implementation:

ADelegateClient* client = [ADelegateClient new];
[SingletonService service].delegate = (id<SingletonServiceDelegate>)client;
[client release];
// you must [SingletonService service].delegate = nil; Since
// [SingletonService service] cannot know the delegate is not pointing to something valid anymore
[[SingletonService service] makeStuffWillCauseCallBackToDelegate];

I didn't read Ray code, if your problem is not similar to this, then i look deep further. But i'm 99% sure it's related to a deallocated pointer problem;