NSFetchedResultsController不将数据更新到UITableViewController

Question

I have the function:

- (void)initFetchRequest
{
    NSManagedObjectContext *context = self.managedObjectContext;
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    request.entity = [NSEntityDescription entityForName:@"Shindy" inManagedObjectContext:self.managedObjectContext];
    // Configure the request's entity, and optionally its predicate.
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"details" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
    [request setSortDescriptors:sortDescriptors];

    fetchedResultsController = [[NSFetchedResultsController alloc]
                                              initWithFetchRequest:request
                                              managedObjectContext:context
                                              sectionNameKeyPath:nil
                                              cacheName:nil];

    NSError *error = nil;
    [self.managedObjectContext executeFetchRequest:request error:&error];
    [fetchedResultsController performFetch:&error];

    if (![self.fetchedResultsController performFetch:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    }    
}

With the following within my viewDidLoad method

NSURL *url = [NSURL fileURLWithPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]];
document = [[UIManagedDocument alloc] initWithFileURL:url];
self.managedObjectContext = document.managedObjectContext;

[self initFetchRequest];

And finally, this within my cellForRowAtIndexPath

Shindy *shindy = [fetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = shindy.details;

Data is being inputted from another controller, and when I segue back to this controller, the UITableViewController isn't updating.

What am I missing here?

Answer 1

If you are coming back from another View Controller (eg with pop in a navigation controller), your viewDidLoad is not called. Therefor your data will not be updated. If you want that to happen, you should implement the NSFetchedResultsControllerDelegate and set fetchedResultsController.delegate = self; . It will update your table whenever a change occurs. There is a less elegant solution, to call your initFetchRequest method from viewWillAppear but I would recommend the first solution. Hope this helps!