iOS NSPredicate通过父实体过滤核心数据

Question

所以我迷失在这一个。我正在尝试使用谓词获取父对象的子对象。如果我取出谓词线，它会返回所有特定的帖子。所以我非常肯定它与谓词有关的一个问题。任何帮助将不胜感激！以下是我的设置。

AccountTimeLine - > SpecificPosts（一对多）

核心数据模型：

读取的结果控制器：

- (void)specificPostFetch 
{ 
    DataAccessLayer *delegate = [[DataAccessLayer alloc]init]; 
    self.managedObjectContext = delegate.managedObjectContext; 
    NSString *entityName = @"SpecificPosts"; 
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName]; 
    request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"createdDateSort" ascending:YES]]; 
    request.predicate = [NSPredicate predicateWithFormat:@"accountTimeLine = %@", self.accountTimeLineObject]; 
    [request setFetchBatchSize:20]; 
    self.specificPostFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil]; 
    self.specificPostFetchedResultsController.delegate = self; 
    [self.specificPostFetchedResultsController performFetch:nil]; 
} 

打印出是accountTimeLineObject的用于比较谓词

po self.accountTimeLineObject 
<AccountTimeLine: 0x7c087b70> (entity: AccountTimeLine; id: 0x7c086590 <x-coredata://353F201D-E739-4DD0-BEBF-DAD6101CFE51/AccountTimeLine/p72> ; data: { 
    accountType = 0; 
    nextPageUrl = 515986477864337411; 
    sort = 0; 
    specificPosts = "<relationship fault: 0x7c634590 'specificPosts'>"; 
    userAccountId = 582; 
}) 

Answer 1

尝试把==在你的谓语，而不是单一=：

request.predicate = [NSPredicate predicateWithFormat:@"accountTimeLine == %@", self.accountTimeLineObject];