Adding non-model nodes to an NSTreeController

Question

I have an NSTreeController that manages an entity is a core data model and an NSOutlineView that displays this tree.

I would like the tree to display some special nodes that do not correspond to entities in the underlying core data model. How would I go about doing that? Should I subclass NSTreeController?

Answer 1

Keep in mind you don't have to use NSTreeController even with Core Data. I've always avoided it since it had a pretty bad reputation back in 10.4, even though I heard 10.5 improves things somewhat. In any case, using NSOutlineView's data source methods will give you full control over what's included in the UI. Subclassing NSTreeController might work, but it'll be more challenging than if it were an array controller because it uses shallow proxy objects, not your actual core data entities.