This sample contains a "joystick" view that shows how you can implement a bindings-enabled subclass of NSView.
In addition to supporting basic binding for a sigle value, it responds properly to multiple selection markers. It is discussed in greater detail in "Cocoa Bindings Programming Topics > How Do Bindings Work?" (
User Interface
The user interface is contained in MainMenu.xib.
The main objects instantiated in the nib file are:
* A window that contains
  - A table view to display Position objects.
  - A Joystick view.
  - Text fields to display and edit angle and offset values of the currently-selected Position object.
* An instance of AppController to manage the view and a collection of Position objects.
* An array controller for the App Controller's Position objects.
The classes used in the sample are as follows:
A simple controller object that manages a collection of Position objects containing offset and angle values. It is also responsible for establishing the bindings from the joystick view to the array controller.
The main focus of the sample: A view that displays the angle and offset of an object, and allows those values to be edited graphically. These features also support bindings.
A trivial model class to encapsulate an angle and an offset.