Re: Crash when loading NSViewController view with NSArrayController [solved]
Re: Crash when loading NSViewController view with NSArrayController [solved]
- Subject: Re: Crash when loading NSViewController view with NSArrayController [solved]
- From: Lee Ann Rucker <email@hidden>
- Date: Mon, 01 Oct 2012 12:43:58 -0700
On Sep 30, 2012, at 11:38 AM, Kyle Sluder wrote:
> On Sun, Sep 30, 2012, at 10:57 AM, Lee Ann Rucker wrote:
>> Weird that you didn't get the warning, but we've switched to the pattern
>> of
>>
>> [self addObserver:self forKeyPath:@"ctrl.selectedObjects.someString"...
>>
>> and that's saved countless headaches. You can remove your own observers
>> in dealloc so you never need to worry about when to remove the observer.
>
> Self-observation has always been a code smell to me. I suppose it's a
> lot better now that we have -removeObserver:forKeyPath:context:.
>
> In general, it is not a good idea to rely on -dealloc for cleanup of
> anything other than object references (that is, sending -release to
> strong ivars). Any other resource that requires explicit management
> (NSNotificationCenter registration, KVO, file handles, etc.) should not
> be managed in -dealloc unless that resource is *explicitly* tied to the
> lifetime of the object (a reuse pool, logging).
>
> I'd add and remove my observation in -setCtrl:. Or, since this is a view
> controller, perhaps add an explicit teardown method
> (-removeViewFromWindow or -windowIsClosing or something) and remove my
> observation there.
>
We've tried that. Either way you have to do cleanup somewhere; dealloc isn't the best place, but not all objects have nice convenient teardown hooks like windows and views do. Doing this in a setter means custom setters all over the place, so no nice @synthesize, and fun when a subclass needs to add a different set of observation values. Plus you'll have to call a setter in dealloc or duplicate the removeObserver code, neither of which are optimal.
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