Core data to-many NSPredicate with AND

问题

I'm trying to write a query for the find-as-you-type search bar. What I want to do is query "Kind", and return any Kinds for which there is a LocalName with ('name' LIKE %@ AND localeIdentifier == %@).

If I'm only searching the names (so ignoring the localeIdentifier), I could do something like this:

ANY localized.name LIKE %@

What I want is something more like

ANY localized.(name LIKE %@ AND localeIdentifier == %@)

To sum up, searching "Kind", any one item in the to-many relationship "localized" should match both name and localeIdentifier.

Any ideas for the correct syntax of this?

回答1:

What you want is a subquery. In predicate format syntax:

SUBQUERY(self.localized, $x, $x.name LIKE %@ AND $x.localeIdentifier == %@).@count > 0

where the SUBQUERY expression returns a collection of instances in the self.localized collection that match the predicate in the third argument. Kind instances for which this SUBQUERY expression is non-empty (ie @count > 0) match your desired criteria.

The SUBQUERY expression was introduced in OS X 10.5.

来源：https://stackoverflow.com/questions/2344184/core-data-to-many-nspredicate-with-and