This book will give you a thorough grounding in the principal and supporting tools and technologies that make up the Xcode developer tools suite. Apple has provided a comprehensive collection of developer tools, and this is the first book to examine the complete Apple programming environment for both Mac OS X and iPhone.
This is probably a great book if you are developing iOS applications, but in my case I was more interested in writing C/C++ code, and I found that with a good text editor such as Sublime, and tools such as GitHub, CMake, and Travis-CI, I mostly don't need the tools Xcode provides. Chapter 12 was, however, exceptionally useful as an intro to Instruments. For test-driven development, I preferred "Modern C++ Programming with Test-Driven Development" and GMock, which is widely used.