Presenting a modal view controller using delegate pattern

gistfile1.m

- (void)insertNewObject {
    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
    Book *newBook = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
	
	BookViewController *bookViewController = [[BookViewController alloc] init];
	bookViewController.book = newBook;
	bookViewController.delegate = self;
	[self presentModalViewController:bookViewController animated:YES];
	[bookViewController release];
}

- (void)bookViewControllerDidSave:(BookViewController *)controller {
	NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    NSError *error = nil;
    if (![context save:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }
	[self.tableView reloadData];
	[self dismissModalViewControllerAnimated:YES];
}

- (void)bookViewControllerDidCancel:(BookViewController *)controller {
	NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
	[context rollback];
	[self dismissModalViewControllerAnimated:YES];
}