NSManagedObject的编译器警告

Question

Why do I receive following compiler warning:

Incompatible pointer types sending 'NSManagedObject *' to parameter of type 'ToDoItem *'

at the last line of this method?:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSManagedObject *object = [[self fetchedResultsController] objectAtIndexPath:indexPath];
    self.detailViewController.editToDoItem = object;
}

ToDoItem is a NSManagedObject subclass.

Answer 1

self.detailViewController.editToDoItem expects a ToDoItem object, so you cannot pass an object of the NSManagedObject superclass :

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    ToDoItem *object = [[self fetchedResultsController] objectAtIndexPath:indexPath];
    self.detailViewController.editToDoItem = object;
}