You need to add the new toDoItem to your array as well. Try this :
// Create a new managed object
NSManagedObject *toDoItem = [NSEntityDescription insertNewObjectForEntityForName:@"AUFToDoItem" inManagedObjectContext:context];
[toDoItem setValue:[alertView textFieldAtIndex:0].text forKey:@"itemName"];
[toDoItem setValue:[NSDate date] forKey:@"creationDate"];
[toDoItem setValue:NO forKey:@"completed"];
[self.toDoItems addObject:toDoItem];
[self.tableView reloadData];