On Nov 16, 2012, at 12:37 PM, Kyle Sluder wrote: > On Nov 16, 2012, at 9:29 AM, davel...@mac.com wrote: > >> >> On Nov 15, 2012, at 8:22 PM, Rick Mann wrote: >> >>> >>> On Nov 15, 2012, at 17:04 , Kyle Sluder <k...@ksluder.com> wrote: >>> >>>> Override -didChangeValueForKey:? >>> >>> Apparently we are strongly discouraged from overriding those methods. :-) >>> >>> -- >>> Rick >> >> Is this documented? What would be wrong with overriding it, calling [super >> didChangeValueForKey:] and then doing whatever else you need to do? > > From the NSManagedObject docs: > >> As with any class, you are strongly discouraged from overriding the >> key-value observing methods such as willChangeValueForKey: and >> didChangeValueForKey:withSetMutation:usingObjects:. > > Two theories as to why: > > - People might forget to call super. > - KVO checks to see if -didChangeValueForKey: is overridden, and if not it > calls the IMP directly, bypassing ObjC message dispatch. > > --Kyle Sluder
Ok, thanks for the info. Forgetting to call super doesn't seem like it would cause Apple to "strongly discourage" as there are lots of methods in various Cocoa frameworks where you do need to call super, but I wondered if there were some hidden performance optimizations or if it somehow might break something. I'm just trying to learn - not argue with you. Thanks, Dave _______________________________________________ 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
