Overall one of the (if not the) best and reasonably thorough introductions to Core Data – if you like the tutorials on the Ray Wenderlich website, you'll really like the book-length versions. Their style does however occasionally frustrate – in its use of code clarity for teaching mode, completely ignoring best practices, Swift-y patterns in a book with Swift 4 right there in the title, and refactoring as one builds; in failing to completely follow through on things such as MOC handling when batch operating directly on persistent stores (much less MOC synchronization in general), how to actually get that exported file from the sandbox to a useful place (since that is the whole point of doing so, no?), or when taking the time to mention NSFetchedResultsController can also drive collection views "with some changes" without also taking time to provide a simple snippet on the topic (this is "by Tutorials" after all). And then there are all the exceptionally oddly numbered lists that make one wonder if this edition was slapped together without so much as a single actual proofread.