outlineView(_:numberOfChildrenOfItem:)

Declaration

@MainActor optional func outlineView(_ outlineView: NSOutlineView, numberOfChildrenOfItem item: Any?) -> Int

Parameters

• outlineView:

  The outline view that sent the message.

• item:

  An item in the data source.

Return Value

The number of child items encompassed by item. If item is nil, this method should return the number of children for the top-level item.

Discussion

The outlineView(_:numberOfChildrenOfItem:) method is called very frequently, so it must be efficient.

See Also

Instance Methods

• outlineView(_:acceptDrop:item:childIndex:)
• outlineView(_:child:ofItem:)
• outlineView(_:draggingSession:endedAt:operation:)
• outlineView(_:draggingSession:willBeginAt:forItems:)
• outlineView(_:isItemExpandable:)
• outlineView(_:itemForPersistentObject:)
• outlineView(_:namesOfPromisedFilesDroppedAtDestination:forDraggedItems:)
• outlineView(_:objectValueFor:byItem:)
• outlineView(_:pasteboardWriterForItem:)
• outlineView(_:persistentObjectForItem:)
• outlineView(_:setObjectValue:for:byItem:)
• outlineView(_:sortDescriptorsDidChange:)
• outlineView(_:updateDraggingItemsForDrag:)
• outlineView(_:validateDrop:proposedItem:proposedChildIndex:)
• outlineView(_:writeItems:to:)