Yep things like this, lack of class prefix, and using [NSDictionary dictionaryWithObjectsAndKeys:@"application/json", @"accept", nil] instead of modern literal syntax @{"accept": @"application/json"} are a bit of a red flag for me.
Although I tend to agree, and I understand they might have their Java devs do the OBJ-C library, but I still wanna' give them the benefit of the doubt, in any case, it's easy to fix.
Most of the library seems pretty straight forward. I will have to dig deeper when I get some time over. I'm debated wether or not to use this as work for a project.
I still doubt as much thought has gone into it as a more mature library like AFNetworking (https://github.com/AFNetworking/AFNetworking) though. Even then the new NSURLSession APIs in iOS7 pretty much remove the need for a 3rd party networking lib.