Returns a Boolean value that indicates whether a drag operation is allowed.
- macOS 10.4+
The table view that sent the message.
An index set of row numbers that will be participating in the drag.
The pasteboard to which to write the drag data.
YES if the drag operation is allowed,
a after it has been determined that a drag should begin, but before the drag has been started.
To refuse the drag, return
false. To start a drag, return
true and place the drag data onto
pboard (data, owner, and so on). The drag image and other drag-related information will be set up and provided by the table view once this call returns with