On 1 Jul 2008, at 17:19, Ron Lue-Sang wrote:
On Jul 1, 2008, at 12:05 AM, Andy Kim wrote:
Thanks - I've seen solutions like this before, I just wanted to
get it working the regular way!
I totally understand the sentiment.
Is itemForPersistentObject expecting an NSTreeNode? You say you
have it working in a similar way - what does your
itemForPersistentObject method return?
Many thanks
Ian
Here's what I do:
- (id)outlineView:(NSOutlineView *)ov itemForPersistentObject:
(id)object
{
return [[gAppDelegate library] groupWithUID:object]; // This
fetches the group from the managed object context
}
- (id)outlineView:(NSOutlineView *)ov persistentObjectForItem:
(id)item
{
return [item uid];
}
According to the docs I'm supposed to archive the persistent object
before returning it, but in my case, it doesn't matter because it's
just a string and it all goes into a plist anyway. I have tried it
both ways after seeing your implementation though, and there are
indeed no differences.
I see why you're thinking that you need to return a NSTreeNode
though. I don't need to do that because I don't use a
NSTreeController and instead implement the data source protocol in
my custom controller. So for me the item is the model object itself.
In your case, I'm fairly positive that you do need to return the
NSTreeNode object. Instead of fetching the model object, walk the
controller's content tree looking for the right representedObject
with the UID.
- Andy Kim
Andy, you're right.
Ian's code needs to return an NSTreeNode. Please file a bug that
this is too hard.
I played around some more with this and came to the conclusion that
it's impossible to implement auto saving of expanded items using
itemForPersistentObject and persistentObjectForItem NSOutlineView
delegate methods, when the outlineview has an NSTreeController as it's
datasource.
The reason I think this, is that the outlineview is populated with
instances of NSTreeNode. At application launch,
persistentObjectForItem is called before the tree has been populated.
I think what goes on behind the scenes, is that a record of which
nodes are expanded and which are collapsed is saved in the app
defaults, persistentObjectForItem is called to get the object in
question and next time the outlineview 'sees' that object from it's
datasource it knows whether to expand that node or not.
The trouble is, the outlineview will never 'see' *anything* you return
in persistentObjectForItem since all it will ever see are NSTreeNode
instances none of which exist yet.
Hope that makes sense! AFAIK, it's not just hard, but un-doable!
Thanks everyone for your help - I've gone over to the regular
datasource way of doing things and everything's swell.
Cheers
Ian
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