NSFetchedResultsController loses his rows after entering background - ios

Question

I've a strange problem in my app.
I instanciate a NSFetchedResultsController to populate my array.
It's declared this way (as a #propoerty (nonatomic, retain) )
- (NSFetchedResultsController *)fetchedContactsController {
if (self->fetchedContactsController != nil) return self->fetchedContactsController;
// Create the fetch request
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// I want every contact...
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Contact" inManagedObjectContext:self->managedObjectContext];
[fetchRequest setEntity:entity];
// ... whose are not associated with my order item
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"NOT (%# IN items)", self.orderItem];
[fetchRequest setPredicate:predicate];
// Edit the section name key path and cache name if appropriate
self.fetchedContactsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self->managedObjectContext sectionNameKeyPath:nil cacheName:nil];
[aFetchedResultsController release];
[firstnameSortDescriptor release];
[lastnameSortDescriptor release];
[sortDescriptors release];
[fetchRequest release];
// Execute the fetch request
[self->fetchedContactsController performFetch:nil];
return self->fetchedContactsController;
}
of course, contacts.items exists.
When my app goes background then foreground again, if I do another
NSLog(#"before >>> %d", [[fetchedContactsController fetchedObjects]count]); // >>> 3
[self->fetchedContactsController performFetch:nil];
[tableView reloadData];
NSLog(#"after >>> %d", [[fetchedContactsController fetchedObjects]count]); // >>> 0
every line in my array disappear !
EDIT :
If I comment these lines :
// ... whose are not associated with my order item
//NSPredicate *predicate = [NSPredicate predicateWithFormat:#"NOT (%# IN items)", self.orderItem];
//[fetchRequest setPredicate:predicate];
The problem don't occur anymore ! But that's not what I want...

Answer 1

Ok I found it. Thanks to this question, I replaced this line :
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"NOT (%# IN items)", self.orderItem];
by
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"NOT SELF IN %#", self.orderItem.recipients];
It's funny how the fact you ask a question can make you on the path to resolve.