On Oct 14, 2013, at 14:12 , Jens Alfke <[email protected]> wrote: > > On Oct 14, 2013, at 1:33 PM, Rick Mann <[email protected]> wrote: > >> I have a tree controller bound to an array in my window controller. I >> populate it with top-level items, and they show up, but I'd like to defer >> populating the children of each item until the user actually clicks the >> disclosure triangle. Getting the children is time-consuming and expensive. >> Is there a way I can get it to show the disclosure triangle and then call me >> back when it's clicked open? > > In your model class implement a boolean property that returns YES for a leaf, > and set that as the NSTreeController’s leafKeyPath. Then the controller will > just call that for closed items and draw the disclosure triangles for items > where it returns NO. > > Then you’re free to make the children and (optionally) count properties > compute the children lazily, because they won’t be called until the item is > flipped open in the UI.
Thanks, Jens, that seems to work well. -- Rick
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