NSFetchedResultsController with NSPredicate not updating - core-data

Question

I fetch data from a Core Data-base and present them in a UITableView. I use a NSFetchedResultController to fetch the data. I want the user to be able to search in the database, and to do that I use a NSPredicate.
The data is presented in the UITableView and everything works well until I set the NSPredicate to the NSFetchedResultController.
I use this in the ViewDidLoad method:
self.fetchedResultsController = nil;
fetchedResultsController_ = nil;
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
exit(-1);
}
and when the user has entered a text from the UITextField, that text will go to the new NSPredicate.
This is done when the search starts:
NSPredicate *pred = nil;
pred = [NSPredicate predicateWithFormat:#"(Designation BEGINSWITH '22')"];
[fetchedResultsController_.fetchRequest setPredicate:pred];
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
exit(-1);
}
[tView reloadData];
Right now I use #"(Designation BEGINSWITH '22')" for testing only.
This is my NSFetchedResultsController:
- (NSFetchedResultsController *)fetchedResultsController {
if (fetchedResultsController_ != nil) {
return fetchedResultsController_;
}
/*
Set up the fetched results controller.
*/
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Product" inManagedObjectContext:importContext];//self.managedObjectContext
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"Designation" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:importContext sectionNameKeyPath:nil cacheName:#"Root"]; //self.managedObjectContext
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor release];
[sortDescriptors release];
return fetchedResultsController_;
}
The problem is that the fetched data stays the same, no matter how or if I set a predicate. If I would set a predicate in the viewDidLoad it would work, but then I wouldn't be able to get new results if I'd tried that again. I use an "importContext" for a batch-import of my CoreData.
Any ideas?
Thanks in advance!
UPDATE:
Ok, here is what I found out. I have an importContext where I make a batch-import. And for the fetchController I use self.managedObjectContext. That's why it doesn't work, so I have to make self.managedObjectContext have the same stuff as my importContext somehow...

Answer 1

You're using a cache (#"Root")… Try setting it to nil, this could prevent crashes. You should not cache FetchedResultsControllers meant to be Predicated.

Answer 2

Even better than setting the cache to nil is giving it a unique name. After posting this question
iPhone - Cache name for NSFetchedResultsController
I added a function to generate UUIDs as my cache names.