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From: | Markus Hitter |
Subject: | Re: Key Value Observation is over reacting |
Date: | Fri, 14 Dec 2007 02:11:02 +0100 |
Am 13.12.2007 um 21:12 schrieb Fred Kiefer:
I just see that this special case is not failing there. Should I set breakpoints on methods of the watched instance and check the back trace for on the fly methods?
Yes, why not?As for the remaining part, I can't see when the getter method would be used inside KVO at all. Notifications are sent on value changes only, which does the setter. Where does the conflict arise?
Until today, I always thought KVO is based on a mini notification center inside NSObject's -setValue:forKey:. This method would try a few ways to get the variable set, then send a notification to all subscribers on success. No need to patch existing classes.
However, this morning I learned, Apple uses something they call "isa- swizzling":
<http://developer.apple.com/documentation/Cocoa/Conceptual/ KeyValueObserving/Concepts/KVOImplementation.html#//apple_ref/doc/uid/ 20002307>
Markus - - - - - - - - - - - - - - - - - - - Dipl. Ing. Markus Hitter http://www.jump-ing.de/
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