Chapter One

Mac OS X is a departure from previous operating systems both on mainframes and on personal computers. Its structure is thoroughly modern—it is based on a small kernel that isolates the most critical aspects of the operating system, and it is object oriented to a degree that has not been seen in a mainstream operating system. Its user experience has been developed based not only on Apple's years of research and development in this area, but also on the powerful processors of today and tomorrow that can provide a rich, sophisticated, and delightful user experience of greater elegance and power than their earlier incarnations could provide.

This book is for Mac OS X developers—for people who are starting to explore Mac OS X to find out what's there and what the opportunities are. It is about writing software and about how Mac OS X makes the developer's job much easier—and very different.

Writing computer software can be very rewarding—both intellectually and financially. Yet it requires scrupulous attention to detail and often consists of continuing repetitions of nearly similar tasks—tasks that must be carried out with attention and accuracy, despite their likenesses. Errors can cause immediate problems, or they can lie in wait until a particular combination of circumstances conspires to loose their destructive forces on unsuspecting people.

The work is extraordinarily labor intensive, consuming large amounts of the lives of often highly paid people while requiring them to repeat (not mindlessly but mindfully) the same tasks over and over, at the same time exacting high