Why zone is always nil while implementing NSCopying?

Question

It may be simple question, but why implementing NSCopying protocol in my class, I get zone == nil

- (id)copyWithZone:(NSZone *)zone
{
    if (zo         


        

Answer 1

NSZone is now an undocumented class because it is quite old, its purpose was to allocate objects on the heap using the same set of virtual memory pages. However it is mostly not used anymore, but since it was used before, that parameter is still there for backwards compatibility.