Coredata on iphone: I can delete data only if I restart the application

I've a simple applications that lets you create groups of people form persons in your AddressBook... So Groups and Persons are in a one-to-many relationships, since a Group can have multiple persons. That's not a many-to-many since I create my own model of Person.

Adding data works without problems.

Deleting data doesn't. If I create a new Person, I must restart the app to delete it or the to delete the Group that Person belongs. Otherwise I get a "EXC BAD ACCESS" in the console. With NSZombieEnabled in the enviroment I get -[CFString release]: message sent to deallocated instance 0x75140d0.

I start with the CoreData stuff automatically created by XCode, create the RootViewController (subclass of TableViewController), I pass it the context and put it in a NavigationController.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

//Creo il controller root e gli passo il context
RootViewController *rvc = [[RootViewController alloc] initWithStyle:UITableViewStylePlain];
rvc.context = [self managedObjectContext];

//Creo il navcon, gli associo il root e lo rendo visibile
navCon = [[UINavigationController alloc] initWithRootViewController:rvc];
[window addSubview:navCon.view];
[window makeKeyAndVisible];

[rvc release];
return YES;

}

The RootViewController shows the Groups, then clicking on a row lets you modify persons in开发者_开发技巧 that group, passing the "nuovogruppo" (the Group Model associated with that row)

- (void)showPersoneControllerWithGruppo:(Gruppo *)nuovogruppo {

PersoneController *pc = [[PersoneController alloc] initWithStyle:UITableViewStylePlain];
pc.gruppo = nuovogruppo;
pc.context = self.context;
pc.delegate = self;
//NSLog(@"%@",[gruppi objectAtIndex:indexPath.row]);
[self.navigationController pushViewController:pc animated:YES];
[pc release];

}

And this is how I delete the person (gruppo is the Group model these persons belong to, persone is an array filled with these persons on viewDidLoad, removeGPObject is an accessor method generated by XCode (Group to Persons relationship))

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

if (editingStyle == UITableViewCellEditingStyleDelete) {
    [gruppo removeGPObject:[persone objectAtIndex:indexPath.row]];
    [persone removeObjectAtIndex:indexPath.row];
    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationLeft];
    NSError *error;
    [context save:&error];
}

}

I hope someone can help me...

UPDATE

Since I was having errors about messages sent to already released instances I tried commenting out all the [... release] lines and finally find out what was causing the problem. The problem was in the creation method of the record and not in the deleting method. Here is the method I use to create it. The line that was causing the roblem is [NomeCognome release] I'd be very grateful if someone could explain me why this line crashes the app.

- (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier {

if (property == kABPersonPhoneProperty) {
    ABMultiValueRef phoneProperty = ABRecordCopyValue(person,property);
    NSString *phone = (NSString *)ABMultiValueCopyValueAtIndex(phoneProperty,identifier);
    NSString *firstName = (NSString *)ABRecordCopyValue(person, kABPersonFirstNameProperty);
    NSString *surname = (NSString *)ABRecordCopyValue(person, kABPersonLastNameProperty);
    NSString *NomeCognome = [NSString stringWithFormat:@"%@ %@", firstName, surname];
    [firstName release];
    [surname release];

    Persona *persona = (Persona *)[NSEntityDescription insertNewObjectForEntityForName:@"Persona" inManagedObjectContext:context];
    persona.ABRR = phone;
    persona.NomeCognome = NomeCognome;
    [phone release];
    [NomeCognome release]; //This line makes the app crash!!! Why???

    [gruppo addGPObject:persona];

    NSError *error;
    [context save:&error];
    [self.delegate PersoneControllerDidSave:self];
    [self loadContentAndReload:YES];
    [self dismissModalViewControllerAnimated:YES];
}

Why that line crashes the app?

Use reloadData method at the end as the following.

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

if (editingStyle == UITableViewCellEditingStyleDelete) {
    [gruppo removeGPObject:[persone objectAtIndex:indexPath.row]];
    [persone removeObjectAtIndex:indexPath.row];
    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationLeft];
    NSError *error;
    [context save:&error];
    [tableView reloadData];
}

It may work now.