> On Aug 10, 2016, at 11:32 PM, Sasikumar JP <jps...@gmail.com> wrote: > > Hi, > > This may be very basic question. I am curious to know the details. > > what was the reason NSNumber conforms to NSCopying protocol. > > NSNumber is immutable class, Making a copy of NSNumber object returns the > same reference. > > Is there any case where NSNumber returns the new object? if not, then what > is the purpose of conformance to NSCopying protocol.
There is nothing stopping a developer from subclassing NSNumber, and if that developer decided to create MyMutableNumber that otherwise conformed to the NSNumber interface, the developer would need to implement -copyWithZone: to do the right thing. If NSNumber doesn’t implement NSCopying, then the subclasser can’t hope to get the correct behavior in this case. -- David Duncan _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
