Re: viewDidLoad and KVO
Re: viewDidLoad and KVO
- Subject: Re: viewDidLoad and KVO
- From: Alejandro Visiedo García <email@hidden>
- Date: Thu, 05 Jun 2014 15:26:02 +0200
Why don't you use viewWillAppear and viewDidDisappear, to register and unregister observers to your foo property object?
If you don't use ARC, be carefull to unregister on dealloc too!
> El 05/06/2014, a las 09:30, Rick Mann <email@hidden> escribió:
>
>
>> 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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