NSPredicate with SubQuery

问题

I have this relationship:

player <—>> games <<—> quiz

and want to get all quiz not in a game of a player, like

SELECT * 
FROM ZQUIZ 
WHERE Z_PK NOT IN (SELECT ZQUIZ 
                   FROM ZGAME 
                   WHERE ZPLAYER == 1)

Can anybody help?

回答1:

This can be done with a SUBQUERY clause. If myPlayer is the player in question:

let predicate = NSPredicate(format:"SUBQUERY(games,$g, $g.player == %@).@count == 0", myPlayer)

来源：https://stackoverflow.com/questions/35688892/nspredicate-with-subquery