iOS8: Day-by-Day is a review of the the most significant new features available to developers in iOS 8. Busy developers don't have time to trawl the WWDC videos and Apple documentation. Instead they'd like to get a high-level summary of the new possibilities, alongside some working sample code. This is exactly what iOS8: Day-by-Day provides. It started out as a blog series, and these blog posts now form the basis of the book.