我正在尝试过滤一些托管对象。结果虽然是zip。
过滤器为“名称”。名称是由根视图提供给此详细信息视图的元素。名称记录确定：
[48582:2754928] name: To Be
[48582:2754928] predicate: name == @"name"
name = [self.detailItem valueForKey:@"name"];
NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) {
// Update to handle the error appropriately.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
exit(-1); // Fail
}
FetchResultsController如下：
NSError *error = nil;
name = [self.detailItem valueForKey:@"name"];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"VerbEntity" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
predicate = [NSPredicate predicateWithFormat:@"name == %@",@"name"];
NSLog(@"name: %@", name);
fetchRequest.predicate = predicate;
NSLog(@"predicate: %@", predicate);
// Create the sort descriptors array.
NSArray *sortDescriptorArray = nil;
// Declare sort descriptors
NSSortDescriptor *sortDescriptorPrimary = nil;
sortDescriptorPrimary = [[NSSortDescriptor alloc] initWithKey:@"position" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];
// Set sort descriptor array
sortDescriptorArray = @[sortDescriptorPrimary];
// Apply sort descriptors to fetch request
[fetchRequest setSortDescriptors:sortDescriptorArray];
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
NSLog(@"fetchedObjects count: %lu", (unsigned long)fetchedObjects.count);
_fetchedResultsController.delegate = self;
return _fetchedResultsController;
}
有什么特别突出的吗？谢谢你的帮助。
似乎您的_fetchedResultsController没有设置获取请求。也许不只此代码段显示了...但这可能行得通
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"VerbEntity"];
request.predicate = [NSPredicate predicateWithFormat:@"name == %@",@"name"];
// Note: Sort descriptors available depend on the backing store type.
NSSortDescriptor *sortDescriptorPrimary = [[NSSortDescriptor alloc] initWithKey:@"position"
ascending:YES
selector:@selector(localizedCaseInsensitiveCompare:)];
request.sortDescriptors = @[sortDescriptorPrimary];
// The request needs to be set on the controller.
NSFetchedResultsController *controller =
[[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
// The controller needs to perform the fetch.
[controller performFetch:nil]; // Optionally pass in an NSError.
controller.delegate = self;
_fetchedResultsController = controller;
return controller;
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