Core data CoreData：多对多关系

我有两个对象，具有多对多关系

这是我的密码：

+ (NSSet *)activitiesSetForMember:(Members *)member inManagedObjectContext:(NSManagedObjectContext *)context{
NSSet *activitiesSet = nil;

NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:@"CompanyActivity" inManagedObjectContext:context];
request.predicate = [NSPredicate predicateWithFormat:@"hasMembers contains %@", member];
NSError *error = nil;
activitiesSet = [[context executeFetchRequest:request error:&error] lastObject];
[request release];

NSLog(@"count: %d", [activitiesSet count]);

//se o array vem vazio (nil), não existe a o tipo de Membro
if (!error && !activitiesSet)
    NSLog(@"Error: Member has no Activities related.");

return activitiesSet;   
}

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如何从选定的

成员

获取所有

活动

？我如何构造请求？do give me？

正如您可能已经怀疑的那样，您的谓词有问题：

也许你感到困惑是因为你命名关系的方式。这些名称似乎表明，在概念上存在一些混乱。我建议您重命名实体和关系，如下所示：

Members         - Member
CompanyActivity - Activity
memberActivity  - activities
hasMembers      - members

有更好的解决办法。属性活动是否已经完全包含您想要的活动？因此：

activitiesSet = member.activities; // according to my naming scheme

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谢谢第一个建议很好。我是CD的新手。第二条评论是正确的。不用去拿了。谢谢，RL