Building Cocoa Applications: A Step by Step Guide

Basic Principles of the Aqua Interface

Before the release of the original Macintosh, different applications running on the same computer in environments such as MS-DOS had wildly different interfaces. Some applications used the mouse; others used only the keyboard. Some applications were character-oriented; others created their own primitive window systems. This was a heavy burden on users and severely limited their overall productivity.

One of the primary goals of the original Macintosh was that different applications running on the same computer would have a consistent user interface. Consistency helps users because they don’t have to learn a new set of rules to perform the same basic operations as they move from application to application. (Think of how easy it is to drive different brands of automobiles — no additional training is required because they all have steering wheels, brakes, and accelerators that work the same way.)

The Toolbox, Carbon, and Cocoa

The original Macintosh delivered this consistent user interface through a set of procedures stored in a read-only memory (ROM) called the Toolbox . Developers who wrote applications for the Mac, regardless of whether they were writing a word processor or a spreadsheet, were encouraged to use the Macintosh Toolbox to display the application’s user interface. This made things easier for users, because all applications behaved in the same way. It also made things easier for developers, because they did not have to reimplement ...