I've read the book (the pre-release and the final release) and it is currently the best Swift book I've read. For a book author, it is probably always difficult

I've read the book (the pre-release and the final release) and it is currently the best Swift book I've read. For a book author, it is probably always difficult to decide which topics to include and which to leave out, and then how much time to spend on a given topic. Advanced Swift does really well here. They explain some of the most-used concepts in Swift in a very detailed way (like Collections, Optionals, Protocols, or Value Types) but also include a couple of advanced topics which you might run into less often, but which are usually complicated and error prone to get right (like using C libraries or String internals). Highly recommended, great book.