Re: Crash in KVO when using -keyPathsForValuesAffecting<Key>
Re: Crash in KVO when using -keyPathsForValuesAffecting<Key>
- Subject: Re: Crash in KVO when using -keyPathsForValuesAffecting<Key>
- From: Quincey Morris <email@hidden>
- Date: Sun, 21 Jun 2009 02:26:17 -0700
On Jun 20, 2009, at 14:15, Jean-Daniel Dupas wrote:
Thank you for the suggestion, but it does not solve the problem.
Even trying w1.object = nil before unregistring the observer has no
effect.
When I looked at your code a little harder, I realized my theory could
not have been correct anyway. For a start, the MyObject was being
leaked, so its dealloc would never be called.
On Jun 20, 2009, at 11:08, Jean-Daniel Dupas wrote:
[w1 removeObserver:foo forKeyPath:@"name"];
[w1 release];
Interestingly, changing this to:
[w2 removeObserver:foo forKeyPath:@"name"];
[w2 release];
works just fine, thought it ought to have exactly the same behavior as
the original version. So here's a new theory ...
The observations you set up manually *both* cause a secondary/indirect
observation, where 'foo' observes (in effect if not actually) the
"name" property of the *same* MyObject. In effect, you have the same
observer object observing the same property of the same target object
twice. (That's something you can't do directly, AFAIK.)
When a secondary/indirect observation needs to be removed (either
because a manual observation is removed, or -- as we discovered when
you tried 'w1.object = nil' -- for a different reason) it looks like
the wrong one can get removed. Or something like that.
Gratz. That's a very elegant bug. :)
_______________________________________________
Cocoa-dev mailing list (email@hidden)
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:
This email sent to email@hidden