Expanding items in NSOutlineView with Core Data
Expanding items in NSOutlineView with Core Data
- Subject: Expanding items in NSOutlineView with Core Data
- From: Ross Winn <email@hidden>
- Date: Sat, 6 Aug 2005 11:08:36 -0700
I am having difficulty with the exact same issue as was discussed in
this thread. The solution, however, was not posted. So I am at a loss...
I have a NSOutlineView that is being populated by bindings from core
data. In my data model I have an attribute that says if the item
should be expanded or not. I know how to expand the items, but if I
try and do it in outlineView: willDisplayCell: (etc) it just
overwrites the other values in the NSOutlineView's root level.
(please see below for more clarification).
The solution was described as "external method of expanding/
collapsing rows" but I'm not sure how to go about calling an external
method after the NSOutlineView has been populated.
Any suggestions are appreciated!
- Ross
Hello,
I have a bunch of items in an NSOutlineView. I have implemented my own
trivial system to store their settings, like the expanded / collapsed
state, et.c. When the NSOutlineView is about to be displayed I check
which items should be expanded in this method:
- (void)outlineView: willDisplayCell: forTableColumn:item:
and call the [outlineView expandItem:item] / [outlineView
collapseItem:item] appropriately.
Now, the problem - as has been described previously on macosx-dev - is
that the outline view seems to have decided how many items to display
beforehand, and doesn't update that value based on wether I later
expand / collaps items or not. The result is that the list of items in
the outline view is cut off after the number of top level items.
Does this make sense? ;)
I think that Richard Schreyer described it better then I do:
On onsdag, februari 21, 2001, at 04:29 , Richard Schreyer wrote:
> When I call reloadData after some change, the Outline View asks
for the
> number of items on the top level, and then only displays that
number of
> expanded items, cutting off the list halfway through (I might
only have
> 5 top level items, but 9 total items that need to be displayed when
> things are expanded.).
> Resizing (and in this case, the drawer containing the outline
opening)
> the view causes the missing items to appear.
> I've tried sending setNeedsDisplay:YES to the outline view right
after
> sending expandItem, but this had no effect.
> Is there a way I can get the outline view to redisplay itself
after it
> creates new items?
Solutions to this problem, anyone? Should I change the expanded /
collapsed state on items somewhere else in the delegate / data source?
I think that you are supposed to be able to have the expanded /
collapsed state stored if you use the itemForPersistentObject /
persistentObjectForItem methods for the outlineView, but I cannot use
them in my app because of my data model that needs to be more
flexible.
Regards,
j o a r
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