I have a custom <NSOutlineViewDataSource>, for which I would its NSOutlineView to update a selectionIndexPaths property. I can’t get bind:toObject:withKeyPath:options: to actually bind properly. Basically, I need my data source to know which item is selected.
When I bind to selectionIndexes (declared by NSTableView) or selectionIndexPaths (declared by NSOutlineView), which the documentation indicates I should be able to (unless for some reason that’s only available in IB), I get a runtime exception that the outline view isn’t “key value coding-compliant” for either of those keys.
When I bind to selectedRowIndexes (a fallback, since I would need to then take that information and reverse-engineer it to figure out which parent/child pair is selected), it updates the data source once, with the NSIndexSet in the data source frozen to its initial value. I don’t set it manually, either. Further, I can’t even bind selectedRowIndexes in the other direction, so the data source can update the outline view’s selection. I get the same “key value coding-compliant” exception on the outline view.
I have an @property defined in my data source class, with a backing ivar, and I’m binding it from a controller class with references to the data source and the outline view, after data has been loaded, in -awakeFromNib.
Rather than binding
selectionIndexPaths, which acted unreliably, I instead used my outline view’s delegate to update the selection in the model on the-outlineViewSelectionIsChanging:and-outlineViewSelectionDidChange:notifications.