Re: viewDidLoad and KVO
Re: viewDidLoad and KVO
- Subject: Re: viewDidLoad and KVO
- From: Rick Mann <email@hidden>
- Date: Thu, 05 Jun 2014 00:30:54 -0700
On Jun 5, 2014, at 00:26 , Lee Ann Rucker <email@hidden> wrote:
> If you're doing something like this:
>
> - (void)setFoo: (Foo *)aFoo
> {
> [foo removeObserver:self forKeyPath:@"whatever"...];
> foo = aFoo;
> [foo addObserver:self forKeyPath:@"whatever"...;
> }
>
> we used that pattern for a while but were constantly getting bit by observers on objects being dealloced or KVO firing and triggering unwanted side effects if we called setFoo: in dealloc. So we did a complete switch over to doing
>
> [self addObserver:self forKeyPath:@"foo.whatever"...
>
> in init, and removeObserver in dealloc, because you can remove an observer on yourself in dealloc without the "observers still registered" warning.
>
> Since it's on self, you can set it before foo exists, and setFoo: triggers it. Plus we could use synthesized setters.
I collect the removeObserver calls into an "ignoreFoo" method, and similarly the addObserver in an "observeFoo" method. Then in -dealloc I call -ignoreFoo. I've never run into the (annoying) registration mismatch errors.
Your suggestion is a good one, but I don't think it solves the problem I have of -setFoo: being called before -viewDidLoad (before the IBOutlets are non-nil).
--
Rick
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