Re: KVO - Observing self from self
Re: KVO - Observing self from self
- Subject: Re: KVO - Observing self from self
- From: Joakim Danielson <email@hidden>
- Date: Sun, 2 Jul 2006 11:25:26 +0200
Why don't you use setKeys:triggerChangeNotificationsForDependentKey: ?
http://developer.apple.com/documentation/Cocoa/Conceptual/
KeyValueObserving/index.html#//apple_ref/doc/uid/10000177i
Joakim
1 jul 2006 kl. 17.43 skrev Daniel Jalkut:
I'm using KVO to observe a keypath relative to "self." For example,
I'm observing "myTree.apples" from an object with a keyed object
"myTree."
This is very convenient because it means I don't have to carefully
manage the addObserver/removeObserver status as "myTree" changes.
But I've noticed that KVO, in an attempt to protect me from "bad
stuff" actually limits my ability to use this technique.
In the object's "dealloc" method, it removes observation of itself.
This should have the effect of cleaning everything up, right? But
apparently KVO interferes much earlier - detecting my impending
dealloc and warning me about the fact that there is still an observer:
An instance 0x38f6a0 of class CueSpecifier is being deallocated
while key value observers are still registered with it. Break on
_NSKVODeallocateLog to start debugging.
What's worse, is it apparently then removes the observer for me, so
that when my responsible "self cleanup" occurs moments later, I see
this in the console:
Exception ignored while releasing an object in an autorelease
pool: [<CueSpecifier 0x38f6a0> removeObserver:<CueSpecifier
0x38f6a0> forKeyPath:@"cueHandler.parameterMenuItems"] was sent to
an object that has no observers.
I guess this is tricky because KVO's watch-dogging is happening at
the sneaky isa-swizzling level.
What are my options? Does anybody have a clean solution for
observing self keypaths from self? I could figure out some way to
manually remove observation before being dealloc'd, but at that
point the convenience factor pretty much disappears.
Daniel
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