On 06/11/2009, at 7:35 AM, Steve Steinitz wrote:
> Fritz's idea looks much cooler (I might try it) but for a clumsier solution,
> have you written your own method to add new top-level items? I wonder if an
> IBAction like this would work:
>
> - (IBAction)
> addVisibleTopLevelItem: sender
> {
> YourEntity *invisibleTop = [self topObject];
> YourEntity *newVisibleTop =
> [NSEntityDescription insertNewObjectForEntityForName: @"YourEntity"
> inManagedObjectContext: [context]];
> [newVisibleTop setParent: invisibleTop]; // does your entity have a
> setParent?
> // might also need to add a child to inVisibleTop
> [treeController addObject: newVisibleTop];
> [treeController rearrangeObjects]; // needed?
> }
>
> Something along similar lines seems to work for me.
Thanks. What I've tried, which does seem to work, is overriding
-insertObject:atArrangedObjectIndexPath: and setting the parent explictly if
the item is being inserted at the top level:
- (void)insertObject:(id)object atArrangedObjectIndexPath:(NSIndexPath
*)indexPath
{
NodeObject* item = (NodeObject*)object;
//only add the parent if this item is at the top level of the tree in the
outline view
if([indexPath length] == 1)
{
//fetch the root item
NSEntityDescription* entity = [NSEntityDescription
entityForName:@"NodeObject" inManagedObjectContext:[self managedObjectContext]];
NSFetchRequest* fetchRequest = [[NSFetchRequest alloc] init]; //I'm
using GC so this is not a leak
[fetchRequest setEntity:entity];
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"isRootItem
== 1"];
[fetchRequest setPredicate:predicate];
NSError* error;
NSArray* managedObjects = [[self managedObjectContext]
executeFetchRequest:fetchRequest error:&error];
if(!managedObjects)
{
[NSException raise:@"MyException" format:@"Error occurred during
fetch: %@",error];
}
NodeObject* rootItem = nil;
if([managedObjects count])
{
rootItem = [managedObjects objectAtIndex:0];
}
//set the item's parent to be the root item
item.parent = rootItem;
}
[super insertObject:object atArrangedObjectIndexPath:indexPath];
//this method just sorts the child objects in the tree so they maintain
their order
[self updateSortOrderOfModelObjects];
}
Can anyone see anything wrong with this?
--
Rob Keniger
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