不能在tableView中获取单元格数

I have a main tableViewController, touch a button self.navigation will push addItem viewController, click save self.navigation with pop the add VC, then we're back on the main one, I successfully add and save, also fetch, but when it comes to fetching number of cells, number returns 0, heres the method

我有一个主tableViewController，触摸一个按钮self。导航将推添加视图控制器，点击保存自我。使用pop导航添加VC，然后回到主导航，我成功地添加和保存，也获取，但是当需要获取单元格数时，number返回0，这里是方法

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

id <NSFetchedResultsSectionInfo> secInfo = [[self.fetchedResultsController sections]     objectAtIndex:section];
NSLog(@"No. of cells determined: %lu", (unsigned long)[secInfo numberOfObjects]);
return[secInfo numberOfObjects];

}

NSLog gives me 0, whats the problem, this gave me headache.

NSLog得到0，有什么问题，这让我头疼。

Here's the fetch request:

获取请求:

- (NSFetchedResultsController*) fetchedResultsController {

// Fetch Request
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Goal"
                                          inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"title"
                                                               ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];




// setting _fethcedResultsController
_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                                                managedObjectContext:self.managedObjectContext
                                                                  sectionNameKeyPath:nil
                                                                           cacheName:nil];




// setting _fetchedResultsController to self
_fetchedResultsController.delegate = self; // for the tableview updating thing



// Thats it
return _fetchedResultsController;

}

Please note that when I run a check for items, it's not nil:

请注意，当我检查项目时，它不是nil:

// fetching all items to check how many of them exists
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity: [NSEntityDescription entityForName:@"Goal"
                                     inManagedObjectContext:self.managedObjectContext]];
NSManagedObjectContext *moc = self.managedObjectContext;

NSError *fetchError = nil;
NSArray *goals = [moc executeFetchRequest:fetchRequest error:&fetchError];

NSLog(@"No. of goals: %lu", (unsigned long)[goals count]);
// end of check for items

1 个解决方案

#1

I forgot to put this code of line:

我忘记把这个代码行:

if (_fetchedResultsController != nil) {
    return _fetchedResultsController;
 }

in method

在方法

- (NSFetchedResultsController*) fetchedResultsController;

so before I did, the app always creates new fetchedResultsController and over-write the old one.

在此之前，应用程序总是创建新的fetchedResultsController并覆盖旧的。

#1