ios - 如何使用 predicateWithFormat 查询 NSString 包含在 NSSet 中

Question

使用 StackMob 作为后端。我有一个 Event 实体，它具有称为用户 users 的关系(类型 NSSet)。现在我想获取某个用户的 username 是 @"someuser" 的所有事件。我的代码是这样的:

[self.client getLoggedInUserOnSuccess:^(NSDictionary *result) {
        NSString *currentlyLoggedInUser = [result valueForKey:@"username"];

        NSFetchRequest *request = [[NSFetchRequest alloc] init];
        NSEntityDescription *eventEntity = [NSEntityDescription entityForName:@"Event" inManagedObjectContext:self.managedOjbectContext];
        [request setEntity:eventEntity];

        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY users.username = %@", currentlyLoggedInUser];
        NSLog(@"predicate: %@", predicate);
        [request setPredicate:predicate];
        NSLog(@"request: %@", request);
        events = [NSArray new];
        events = [self.managedOjbectContext executeFetchRequest:request error:nil];

        /* this is working...
        for (Event *e in events) {
            NSLog(@"%@",[e.users filteredSetUsingPredicate:[NSPredicate predicateWithFormat:@"username == %@", currentlyLoggedInUser]]);

        }
         */
        NSLog(@"events: %@", events);
    } onFailure:^(NSError *error) {

    }];

Answer 1

如果我正确理解你的问题，你必须使用以下谓词:

NSString *userName = @"some user";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY users.username = %@", userName];

它会查找具有给定用户名的任何用户的所有事件。