Objective-C Fundamentals

246 CHAPTER 12 Reading and writing application data
insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView
deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[self.tableView
reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
case NSFetchedResultsChangeMove:
[self.tableView
deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
[self.tableView
insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[self.tableView endUpdates];
}
All changes complete, so animate them
What does all this code do? First, in the viewDidLoad method, you set up Edit and
Add buttons. Notice that you get editButtonItem for free from UIViewController. In
the addPerson method, you set up and present the view controller to add a new person.
Next, in the tableView:commitEditingStyle:forRowAtIndexPath: method, you
take care of deleting entries from the managed object context and save it afterwards.
Finally, that really long method at the end, controller:didChangeObject:atIndex-
Path:forChangeType:newIndexPath:, gets called by the NSFetchedResultsController
every time the result set changes in any way. Now when you add or delete a person
from the managed object context, the fetched results controller calls this method, and
it updates the table view because you set the instance of PeopleViewController as the
delegate of the NSFetchedResultsController in listing 12.8.
Build and run your application: you should be able to add and delete people now.
12.4.8 Managing tasks
Okay, you can list, add, and delete people in your application. The only thing missing
is the ability to add tasks to a person. To do that, you create another UITableView-
Controller subclass and call it TasksViewController. It’ll look basically the same as
the PeopleViewController with only a few differences (you can copy and paste the
code from PeopleViewController as a starting point): it’ll have a person instance