Cocoa Design Patterns 1st Edition

This superb book has finally unlocked Cocoa programming! Let me explain.

In most subjects we learn by acquiring a little bit of knowledge and, once that bit has been understood, we move on to the next little bit, until the bigger topic is understood. First we learn A then we learn B. Unfortunately, this method of learning does not work well with application frameworks such as Cocoa. These frameworks usually consist of a number of complex idea that are strongly interrelated. You cannot learn A then B, since A requires B and B requires A. Instead you must learn topics A..Z all at the same time! Cocoa is especially difficult for most programmers since it is based on using Objective C, and Objective C is based on Smalltalk. Smalltalk is an extremely dynamic language whose principles are significantly different than those of current popular languages. Thus, most programmers must learn zilllions of elements of the Cocoa framework and also the unusual ideas behind Objective C (Smalltalk). These are essential since Cocoa works differently than other popular frameworks and cannot be understood without understanding Objective C's dynamic approach to programming.

Up until now we have had Objective C books which help learning Objective C, and the excellent Hillegass book (Cocoa Programming for Mac OS X) which is a tutorial on Cocoa. The Hillegass book does help the reader understand many principals behind Cocoa, but it stops short of giving in depth knowledge of the design patterns that Cocoa uses. Thus when the user tries to go beyond the Hillegass book he/she is frustrated because they were not taught the full idea behind each element of Cocoa and their connections to other elements. There is not enough information for the reader to branch out to develop their own programs.

Cocoa Design Patters, on the other hand, presents, in a very professional manner, the most important Cocoa patterns, in depth, and how they are all inter-related. Furthermore, it presents details how how to use the patterns, examples of where they are used in Cocoa, and includes extremely valuable and unbiased information on the pro's and con's and pitfalls of using each pattern. Although this is certainly not tutorial/beginner information, the book is extremely well written and enjoyable to read (especially for those of us who loved Smalltalk and other dynamic languages). It is one of the best written highly technical books I have ever read (and I have been programming since 1970).

In my opinion this book will save the prospective Cocoa programmer many, many, many hours of frustration. I only wish it had been available several years ago when I first tried to learn Cocoa (I did not succeed then, but I am succeeding now).

One final note. The authors could do the Mac Developer Community, and the wider developer community, an enormous favor. In this book they demonstrate an impressive depth of knowledge about Cocoa, Objective C, the Mac development world, and the XCode tools. It would be fabulous if they were to develop a professional unbiased critique and comparison of the pro's and con's of the Objective-C/Cocoa approach to development with other framework/development environments (e.g. Microsoft's). I think this is especially important since the dynamic language approach to programming has fallen out of favor, yet I think it has many benefits that are seriously under appreciated. This document would:
Clearly show programmers the benefits of the dynamic language / Cocoa approach to programming. Perhaps it would reawaken interest in dynamic languages!
Point out the areas where Objective C/Cocoa/XCode has weakness and should be improved. This may inspire Apple to improve their development tools at a brisker pace.'
The development world has had few breakthrough improvements over the last decade or two. I think that much can be learned from Cocoa/Objective C, and I hope That Cocoa Design Patters is just the beginning of a renewal of interest in this too-long-neglected approach to software development.

This book is not for beginners to Cocoa. I would only recommend it folks that have a reasonable amount of experience with Cocoa / Objective-C. Don't take this the wrong way; I'm only defining the target audience. This book details the patterns at work in Cocoa's architecture. While this text may confuse those new to Obj-C or Cocoa, it provides valuable insight into Cocoa usage patterns.

Cocoa Design Patterns explains techniques commonly used throughout the Cocoa architecture (Model-View-Controller, Release/Retain Counting, Delegates, etc.), and provides concrete implementation examples in the frameworks. For each pattern it also describes the scenario that you may use it in, and the consequences, good and bad, to using the pattern. I would recommend this book to anyone after they've cut their teeth on Cocoa, after writing their first couple simple applications. This book shines light on some of the design decisions Apple made with Cocoa, and helps the reader understand how to best leverage the patterns utilized in the Cocoa frameworks.

It was the iPhone that finally brought me into the world of Cocoa programming. I quickly fell in love with the Cocoa & Cocoa Touch frameworks, finding them to be elegant, consistent and truly useful. I've read several books on Cocoa, Objective-C and Mac / iPhone development, but this one stands alone in its quest to fill the gaps, to cement a deep and thorough understanding of one of the best frameworks ever written.

Simply stated, this book is a joy to read. It answered many questions that I had about the "why" behind the evolution of Cocoa and has left me feeling better able to make the most of its power. Cocoa Design Patterns is written in a style that is extremely accessible. It is almost like a detective novel as each chapter unravels the secrets of Cocoa. The most fun I've had reading a technical book in a long while.

Overall, I thought the book was expertly written. It covers a lot of important and interesting aspects of Cocoa, and all its major patterns. The only reasons I'm not giving it 5 stars are:

- there are several errors in the code samples. Occasional bugs are inevitable, but non-compiling code is inexcusable and a major disappointment, for a book of this nature;
- its coverage of the Singleton pattern is incomplete, considering that it doesn't discuss Apple's own recommendations on how to implement a singleton;
- no discussion of patterns related to thread safety;
- the discussion of HOMs (higher order messages) is interesting, but it strikes me as something rarely used; I'd have preferred if the author had used the space spent on HOMs to discuss something more practical. For instance, a common application of the Proxy pattern is the asynchronous loading of images off the web. I think that would have been more useful;
- later chapters are very repetitive, and much less concrete in actual usage, than earlier ones. For instance, chapters 28 (Managers), 29 (Controllers), and 32 (Bindings and Controllers) have a lot in common, and that commonality is repeated in all 3 chapters. Chapter 31 (Application Kit Views) is a repetition of material covered in several previous chapters and adds nothing new.

I'm a great fan of Design Patterns and think that the Gang of Four book (Design Patterns: Elements of Reusable Object-Oriented Software) is still the best book on the subject. However, it's focused on C++ and not on Objective-C and Cocoa. This book, despite its faults, is a worthy partner to the Gang of Four book and is a great addition to any Cocoa programmer's library.