The Companion Guide is a big help to us readers of your book (well, at least to me!), and I really appreciate you folks taking the time to write it up and make it available. I just hope you’re keeping in mind those of us who have purchased the e-book book version of Cocoa Programming for OS X, which does not contain page number references in any way. For those of us who have the e-book version of Cocoa Programming for OS X, therefore, that makes all of the references to printed page numbers meaningless. In order to locate the text that the Companion is referencing, therefore, the reader has to try and map out (i.e., search) the content of the code snippets seen in the Companion Guide against the e-book. And for some material there is no text at all to search. For example, regarding changes needed to code found in chapter nine, the Companion Guide explains
If I had the printed book, I’d know to limit my search for ‘removal’ references to pages 159 and 160, but because I have no printed book — that is, no way to see paper-related page numbers in my copy of Cocoa Programming for OS X – I have to start at the beginning of chapter nine and hope I hit upon the correct block of text. It’s not impossible to follow such instructions, of course, thanks mainly to the Companion Guide’s subheadings that relate to Cocoa Programming’s chapters, but not being able to reply on the page numbers mentioned in the Companion Guide make that task harder than it should be.
I would urge you, therefore, to go to the trouble to insert references to the page numbers seen in the printed version of Cocoa Programming for OS X when you produce the e-Pub (er, ‘Amazon Kindle’) version of your book, for that will make these sorts of errata much more useable in the future, to say nothing of the help they will be when e-book-version readers wish to make reference to the contents of your books in their various forum posts. I would also urge you to think about offering buyers of your books documents that employ open standards, which you can easily (well, relatively easily) make available at a store other than (or in addition to) Amazon’s site. KF8 (Kindle Format version 8), which I presume is the format you supplied to Amazon, is not an open standard. In other words, make available an ePub and a PDF/A version of the book to persons who buy a given title. If you’re looking for models, you can see such behavior present at sites such as http://abookapart.com and https://www.packtpub.com.
Unfortunately, as of today, adding printed-page-number references to e-books sold at Amazon is not as easy as it should be thanks to their stubborn ways, but it is possible. If you’re not familiar with how to so so, you might start with these two resources and go from there: