Intro
Cocoa - What is it?
Cocoa is Apple Computer's latest Application Programming Interface, a set of libraries and frameworks based off of Objective-C, exclusively set in Mac OS X. Cocoa is relatively new to Apple and its developers, but its roots go back to 1980's when Objective-C and NeXT's software were developed.
Apple's history of Cocoa:
Cocoa is the descendant of NeXTStep and has a rich design history reaching back to 1987. Cocoa is implemented in Objective-C, an ANSI C compatible language with dynamic object-oriented extensions modeled on Smalltalk. It has been tailored for efficient development and runtime performance.
History
Objective-C was created in the early 1980's by Brad Cox. He wanted to create an object-oriented programming language which inherited the principles of Smalltalk. However, he did not want to create an entirely new language, so he based his new languaged heavily off of C, but adding the power of object oriented programming.
Once upon a time, two Steves started a computer company named after a piece of fruit. Several years later, one of the Steves (let's call him Steve Jobs, since that is his name) was ousted from his company by Apple's CEO (who once sold sugar water). Jobs then went off to form another computer company: NeXT Computers, Inc.
For awhile, NeXT built its own software and hardware systems. Over time, the hardware proved to be too expensive, and they stuck with their software, named NeXTStep. In 1996, Apple bought out NeXT, using their technology to provide Apple with a 'modern' operating system. These frameworks and tools which were developed by NeXT evolved into what is now known as Cocoa.
Getting Started
There are those who have said that you can learn Cocoa in the course of an afternoon. This is hogwash. That is as believable as learning C in 24 hours or Java in 21 days.
Cocoa is simply too large to learn in any minute amount of time. Much like any other programming language, Cocoa will take years of experience to become proficient in, and even then, there is no guarantee that you will know or understand everything. However, don't let that stop you.
What should be said is that the basics of Cocoa can be learned in the course of several hours. At first, the syntax of Cocoa looks a little odd, but after working some with this language, the difference in syntax should become a trivial matter. Many of the object oriented concepts which are prevalent in Java are present in Cocoa.