On Jul 18, 2012, at 23:22 , Markus Spoettl wrote:
> That doesn't sound right. The array controller is used by views directly,
> they bind to arrangedObjects (like in the example). Since when is it
> recommended to insert an intermediate object between table view and
> NSArrayController? Makes the whole binding idea rather useless, or am I
> missing something?
I wasn't thinking about inserting an intermediate object there. Rather, I was
thinking of two techniques (and I am sure there are plenty of others) for
preventing KVO operations from triggering unwanted expensive updates:
1. Use the cancelPerform/performSelector…afterDelay:0 pattern to defer the
expensive operation until the next run loop iteration AND prevent it from being
queued more than once.
2. Use a brute force flag when setting the predicate, something like this:
dontStartExpensiveUpdate = YES;
[_arrayController setPredicate: …];
[_arrayController rearrangeObjects];
// at this point, the KVO notification has been sent up to twice, but
ignored each time
dontStartExpensiveUpdate = NO;
… do the expensive update now …
Suggestion #1 would coalesce all rearrangements during a single run loop
iteration (including multiple content changes). Suggestion #2 would just work
around the rearrangement behavior.
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