核心数据谓词＆＃34;无法解析格式字符串＆＃34;

Question

我正在尝试获取一组与其他对象具有特定关系的NSManagedObjects。

所以我有4个托管对象：UserPick，Game，Group，User。 UserPick与Game，Group，User分别有一对一的关系。我需要查找具有特定UserPick，Game和Group的所有User，但我似乎无法正确构建谓词：

我试过了：

[NSPredicate predicateWithFormat:@"%K = %@, %K = %@, %K = %@",
UserPickRelationships.game, game,
UserPickRelationships.group, group,
UserPickRelationships.user, user]

和

[NSPredicate predicateWithFormat:@"%K = %@, %K = %@, %K = %@",
UserPickRelationships.game, game.objectID,
UserPickRelationships.group, group.objectID,
UserPickRelationships.user, user.objectID]

最后：

[NSPredicate predicateWithFormat:@"%K.%K = %@, %K.%K = %@, %K.%K = %@",
UserPickRelationships.game, @"objectID", game.objectID,
UserPickRelationships.group, @"objectID", group.objectID,
UserPickRelationships.user, @"objectID", user.objectID]

我尝试在每个可能的组合中使用%@和%K。我所得到的只有：NSPredicate cannot parse format string。我怎样才能做到这一点？

Answer 1

您可能希望将条件与“AND”结合使用：

[NSPredicate predicateWithFormat:@"%K = %@ AND %K = %@ AND %K = %@",
UserPickRelationships.game, game,
UserPickRelationships.group, group,
UserPickRelationships.user, user]

（假设UserPickRelationships.game评估为字符串"game"）。