Unfortunately, it’s not an upgrade from iOS 10 by Tutorials (just as none of our iOS X by Tutorials books are ever upgraded). But it is on sale for pre-order, if that helps!
@lucianboboc: We’re waiting to see if and when the RxSwift community makes the leap to Swift 4. Once that happens and RxSwift 4 is released, we’ll likely begin the updates to the book. Thanks!