What is the difference between “-copy” and “-copyWithZone:”?

Question

I know that copy creates an immutable copy of an object but i just want to know how copywithzone works and what is the basic difference between copy and copywithzone

Answer 1

copy is just short for copyWithZone:, using the default zone.

it's rare that you would call copyWithZone: directly, although defining/implementing it is required in order to adopt @protocol NSCopying. so you would normally see copyWithZone: only within an implementation of copyWithZone:. similarly, you would typically avoid implementing copy, and just let the default implementation of copy call through copyWithZone:.

Answer 2

NSZone is a legacy concept that has no bearing on iOS. By default -copy on an NSObject will call -copyWithZone: with the default zone.