Databases
StackOverflow2013
Postsdbo
POTableView keeps empty after using NSFetchedResultsController
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POTableView keeps empty after using NSFetchedResultsController
    primarykey
    data
    text
    <p>I've tried to use NSFetchedResultsController in order to display sections to my tableView. But now my tableView keeps empty.</p> <pre><code> @property (nonatomic,strong) NSManagedObjectContext* managedObjectContext; @property (nonatomic, retain) NSFetchedResultsController *fetchedResultsController; - (NSManagedObjectContext *)managedObjectContext { NSManagedObjectContext *context = nil; id delegate = [[UIApplication sharedApplication] delegate]; if ([delegate performSelector:@selector(managedObjectContext)]) { context = [delegate managedObjectContext]; } return context; } - (void)viewDidLoad { self.fetchedResultsController = nil; self.fetchedResultsController.delegate = nil; } - (NSFetchedResultsController *)fetchedResultsController { if (_fetchedResultsController != nil) { return _fetchedResultsController; } NSManagedObjectContext *managedObjectContext = [self managedObjectContext]; // Create and configure a fetch request with the plant entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Travel" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // Create the sort descriptors array. NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:nameDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; // Create and initialize the fetch results controller. NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"country" cacheName:@"country"]; self.fetchedResultsController = aFetchedResultsController; _fetchedResultsController.delegate = self; return _fetchedResultsController; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { // Return the number of sections. return [[self.fetchedResultsController sections] count]; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { id &lt;NSFetchedResultsSectionInfo&gt; sectionInfo = [self.fetchedResultsController sections][section]; return [sectionInfo numberOfObjects]; } - (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { return @""; } </code></pre> <p>I followed a tutorial but the tableView is empty now. My tableView worked before fine (with coreData). Maybe someone knows an answer to my question. Thanks.</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USuser2650439
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COyou should call [self fetchedResultsController] not [self.fetchedResultsController]. You set the latter one to nil in viewDidLoad.
      singulars
      1. POTableView keeps empty after using NSFetchedResultsController
      1. UStheaob
    2. CO@theaob Look at his code, he is lazily loading it in the accessor.
      singulars
      1. POTableView keeps empty after using NSFetchedResultsController
      1. USAbizern
    3. CO@user2650439 Please can you tell me what tutorial you used so I can recommend people avoid it.
      singulars
      1. POTableView keeps empty after using NSFetchedResultsController
      1. USAbizern
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload