Question

我有一个提取请求，该请求从Person实体中提取一堆对象，然后遍历每个对象以查找相关对象中的某些更改。所有这些都在后台队列中发生，其类型为NSPrivateQueueConcurrencyType的托管对象上下文。为了对此进行优化，我想使用setRelationshipKeyPathsForPrefetching，以便该应用程序不会每次都一直访问数据库，但似乎无法正常工作！当查看SQL调试日志时，无论是否设置了setRelationshipKeyPathsForPrefetching，我都会看到相同的输出：

CoreData: annotation: to-many relationship fault "addresses" for objectID 0x9d51b4e7ba39580c <x-coredata://C2C3C38B-31CB-4B1B-8222-63E8B04BB9E8/Person/p1> fulfilled from database.  Got 3 rows
....    
CoreData: annotation: fault fulfilled from database for : 0x9d51b4e7ba395808 <x-coredata://C2C3C38B-31CB-4B1B-8222-63E8B04BB9E8/PersonAddress/p1>

这是我设置NSFetchRequest的方法：

__block NSArray *items = nil;
[context performBlockAndWait: ^{
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext: context];
    [fetchRequest setEntity:entity];
    [fetchRequest setPredicate: [NSPredicate predicateWithFormat: @"isContactArchived == FALSE"]];

    [fetchRequest setRelationshipKeyPathsForPrefetching:@[@"emails", @"phones", @"addresses"]]; // doesn't seem to make a difference (possible because no prefetching is happening according to sql logs?)

    NSError *error = nil;
    NSArray items = [context executeFetchRequest:fetchRequest error:&error];
    NSLog(@"Fetched = %li objects", (unsigned long)items.count);
}];

有任何想法为什么setRelationshipKeyPathsForPrefetching不起作用？我知道我以前有过它，但是那是因为它是一个与NSFetchedResultsController绑定的NSFetchRequest，它可以在主线程上工作，因此将MOC与'NSMainQueueConcurrencyType'一起使用。

核心DatA：使用setRelationshipKeyPathsForPrefetching无效

0 个答案: