dataSource
The object that provides the data displayed by the receiver.
Declaration
weak var dataSource: (any NSOutlineViewDataSource)? { get set }Discussion
The object must implement the appropriate methods of NSOutlineViewDataSource. Note that in versions of macOS prior to v10.12, the outline view did not retain the data source in a managed memory environment.
Setting the data source invokes tile().
If the data source doesn’t respond to all of the outlineView(_:child:ofItem:), outlineView(_:isItemExpandable:), outlineView(_:numberOfChildrenOfItem:), and outlineView(_:objectValueFor:byItem:) methods, an internalInconsistencyException may be raised.