Even though the book was out for over two years when I read the book, it's still a pretty good book that covers a lot of what you need to get started on basic macOS development. If going through the examples, note that the version of Swift in the book is Swift 1, which is fairly different from existing version of Swift (and I would recommend learning Swift from another resource if you want to follow along since their code needs reinterpreting to the current version of Swift, especially if you haven't used Swift before), that built-in classes in Cocoa may have changed their names (though Xcode may help you with this depending on what version you use), and that you may need to add "@objc" attributes to some properties and functions for compatibility (e.g. selectors and KVO).