How to dynamically update an NSTreeController and NSOutlineView?

Question

When an outlineViewItem is expanded -

 (void) outlineViewItemDidExpand:(NSNotification *)notification

-, I'm able to successfully add an object to the TreeController (log statements show the newly added object in the correct place of the hierarchy), but the OutlineView/UI isn't updating to reflect that insertion.

To no avail, I've used

• [self.outlineView reloadItem:nil reloadChildren:YES],

• [self.outlineView reloadData], and even

• [self.outlineView setHidden:YES] then
  [self.outlineView setHidden:NO]

to try to force reload the structure.

This is all done programmatically in Objective-C.

Answer 1

6 hours later, I got it.

I needed to update the NSTreeController cache, which is achieved via the rearrangeObjects method.

So the answer to my question is:

[self.cloudDirectoryTreeController rearrangeObjects];