Predicate on two values
Predicate on two values
- Subject: Predicate on two values
- From: Scott Ellsworth <email@hidden>
- Date: Mon, 27 Jun 2005 15:41:57 -0700
Hi, all.
I cannot figure out how to write a predicate that will query for
objects whose X and Y values are in a list of pairs, both of which
must be satisfied.
Details:
I have a Location attribute in my Core Data model that tells my
program the X and Y location of a graphic. These are modelled as,
appropriately enough, int16 attributes.
I want to find all graphics at certain locations near to a selected
object. Thus, I want to query my store for all Location instances
whose X and Y values are in a list of pairs.
For example, if I am at (1,3), I want to find any locations with
(X,Y) = (3,3) and (1,5), but not (1,3) or (3,5). (The actual list is
about twenty possible points, and will be run a fair number of times.)
I have a function that returns an NSArray of NSNumber instances:
[3,3,3,5,3,1,...], though I also have versions that return an array
of arrays, and one that send back just the x and one that gave back
just the y values.
Obviously, it would not be hard to write a predicate that returned
all locations whose X value was 1 or 3, and Y was 3,or 5, but that
would return points that do not qualify.
Any suggestions on how to approach this?
Scott
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