The Application Kit, also known as the
AppKit framework, contains all the classes needed
to build OS X GUI applications. This is the framework we used in our “Hello
World!” example in Code Example.
AppKit is a very large framework
and this book will not cover all the classes provided. I’ll introduce the
concepts you need to get started and illustrate a few of the classes that
every programmer uses for graphical interfaces.
You need to understand a few key concepts before digging
further into Cocoa. So far, we have looked closely only at the
Foundation classes, which map fairly intuitively
to concepts and library calls in other programming languages and
programming environments. With Cocoa, we jump into unique concepts that
are less intuitive.
Cocoa is a well-thought-out, well-designed, and very consistent API. To assure this consistency, a few key concepts underlie most of the API classes. By following the designed conventions, you will avoid spending a lot of time rewriting your code over and over.
These Cocoa concepts and conventions are unfortunately not enforced in all the available frameworks. Some C-based frameworks were incorporated into Cocoa simply by adding an Objective-C wrapper, and these usually don’t follow the conventions as nicely as frameworks written directly in Objective-C.
Ruby developers who have done any web development should be quite familiar with the model-view-controller (MVC) ...