Re: KVO Question: How to programmatically determine if one object is observing another on a keyPath and context?
Re: KVO Question: How to programmatically determine if one object is observing another on a keyPath and context?
- Subject: Re: KVO Question: How to programmatically determine if one object is observing another on a keyPath and context?
- From: Mike Abdullah <email@hidden>
- Date: Mon, 10 Sep 2012 11:52:52 +0100
On 10 Sep 2012, at 11:40, Motti Shneor <email@hidden> wrote:
> Thanks everyone. You are ALL right in your comments, and still my problem persists.
>
> In reality, I have at least 6 external "triggers" or state-changes that determine (in a quite complicated way) whether or not I should observe that attribute.
>
> The (rather wise!) suggestion to start my key-path at self, and so avoid the need to watch for representedObject changes could cure one of the 6. Still I have the other 5...
>
> My question is general. Supposedly I could NOT start observing once, and stop it once. Reasons:
> 1. There are many instances of that NSViewController
> 2. This observation is quite frequent in time (could reach 100 times a second)
> 3. The code to filter-out unwanted value-changes is CPU intensive. (Accounting for 5 orthogonal conditions, upon which I should actually do something with the attribute change)
>
> So - I'd rather REMOVE the observation when I don't need it.
How much measurement have you done on this? In my experience, often the act of setting up or tearing down an observation is more time-consuming than leaving it running. Once the observation is in place, it's a fairly passive system.
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