I'm confused on what should I use to uniquely identify my users?
I want to support iOS7 too but i dont understand the differences.
I'm currently using this snippet to generate a UUID:
CFUUIDRef udid = CFUUIDCreate(NULL);
NSString* createdUUID = (NSString *) CFUUIDCreateString(NULL, udid);
[createdUUID autorelease];
CFRelease(udid);