With the array controller still selected,
switch to the bindings inspector
Find the Content Array binding in the list and expand it.
Select File's Owner
in the pop-up next to Bind to
and check the box.
Leave the Controller Key blank and
employees for the Model Key Path
Cocoa programmers would say that they are binding the Content Array
of the array controller to the employees array of
(which is an instance of Document).
Figure 9.8 Binding the array controller’s content array
This binding sets up the input of the array controller to be the employees ...