isUnavailable should return YES when not available in that case
CCSectionViewController should return nil;
it could even be removed from here to not initialize the object
without reason and check directly before the allocation, would just be
an optmization, I guess is okay
in CCLoader.xm :
if the initializer return nil, set it in the dictionary would cause
a crash
in CCSectionViewController.xm :
in CCLoader.xm :