On Wed, Mar 16, 2011 at 11:28 AM, Dave DeLong <davedel...@me.com> wrote:
> Directly, yes. NSExpression stores a keypath as a single string, whereas
> variables are store in their own kind of NSExpression object. When you
> replace variables with new values, it's only looking for the certain kinds of
> NSExpression objects to replace. Everything else stays the same.
Well that's a shame. That's also probably why [[NSPredicate
predicateWithFormat:@"SUBQUERY(events, $x, $x = $someVar)"]
predicateWithSubstitutionVariables:[NSDictionary
dictionaryWithObject:@"foo" forKey:@"someVar"]] doesn't work, either.
It skips over the subquery NSExpression.
>
> Some notes about your predicate:
>
> - I'm not sure you can do "$x isKindOfClass: %@" as the predicate to a
> subquery, although I haven't tried it.
You can, but the syntax isn't documented. Then again, much of
NSPredicate is poorly documented.
> If it doesn't work, you could do this with a FUNCTION ("FUNCTION($x,
> 'ks_isKindOfClass:', %@)"). Note, however, that you'd have to create a
> category on NSObject that simply boxes the return value of isKindOfClass into
> an NSNumber. FUNCTION()'s don't like methods that return primitives.
It seems to deal with BOOLs just fine; I believe it's internally
wrapping the value in an NSNumber, much like how arbitrary keypaths
are supported on 10.5 and up (they get wrapped in NSNumbers or
NSValues if necessary).
--Kyle Sluder
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