I’ve recently finished reading Swift for the Really Impatient. It was a really good book; I’d give it 4 out of 5 stars.
I had previously read Scala for the Impatient 
I’d like to make one thing clear for future readers. This book will not teach you to write your first functional OS X or iOS application; it assumes you’re an experienced Objective-C developer wanting to learn Swift’s syntax quickly. It differs in this way from Horstmann’s books, the style of which the authors have attempted to mimic. For example, after reading Scala for the Impatient the reader will be be able to write parsers, perform file and network functionality, as well as design and implement a minimal (yet powerful) distributed event bus using actors. Swift for the Really Impatient won’t teach you any of these types of things. Again, it’s related to Horstmann’s books only by similarity in title.
The book flows very well and very quickly. I read the entire book in my spare time, spanning only a few days. At only about 140 pages, compared to The Swift Programming Language book written by Apple (~600 pages), Swift for the Really Impatient is by far the easiest and quickest book to digest if you want to gain an understanding of Swift. If you’re familiar with Scala, you’ll breeze through this book.
One thing that kept throwing me off in the book was how it really feels targeted toward developers who were previously familiar with Objective-C. This isn’t a bad thing, considering you’ll need to at least understand Objective-C to really dig into OS X and iOS development using Swift. It’s also not a prerequisite for reading and understanding this book. The reason it threw me off is because the book doesn’t really ever explicitly define the target audience as having prior Objective-C knowledge, so sections explaining that “…the syntax of Swift should look familiar to Objective-C developers…” offer very little to developers without Objective-C backgrounds. It is fair to mention that the description on the Amazon product page for the book does clearly define the target audience as experienced Objective-C developers. If you pick this book up having had no prior experience on Apple’s platform, you’ll probably see some of the Objective-C code and think “what the…?!” Good news, though! You should be able to easily glance over the Objective-C parts and still fully understand the syntax of Swift.
I would actually take the authors’ references to Objective-C and expand them a little. Much of the Swift syntax would be familiar to someone with Java, C#, Groovy, or even JavaScript experience. The only places I think some developers may have a hard time are with the sections on Optionals and pattern matching. I felt like the authors excellently explained these concepts, but I’ve experienced first-hand in Scala how Java developers have struggled with these concepts. If you find yourself struggling one these sections, take your time and maybe reread the section (be less ‘Really Impatient’).
I loved how well the authors explained closures. If you have a JavaScript background, the section on closures will make a lot of sense. A book I previously read on Swift application development using Cocoa did a comparatively terrible job explaining closures, so it was refreshing to see the subject clearly and concisely presented in Swift for the Really Impatient.
The book definitely delivers the material you need to quickly understand the capabilities and syntax of Swift. The reason I’ve given it 4 stars instead of 5 is because it doesn’t explain how to execute Swift code. There’s no mention that XCode 6 is required to build and compile Swift. XCode is mentioned only on one page, less than 20 pages from the end of the book. The section mentioned XCode explains how to bridge Swift and Objective-C code which took me a couple of tries to figure out when I attempted this while following Apple’s official documentation. I’d imagine that a truly ‘Really Impatient’ developer would get frustrated with the short explanation of the process.
Swift for the Really Impatient should absolutely be the starting point for any developer hoping to code for Apple products. It is quick, concise, and (most importantly) accurate. I may even go so far as to suggest the book to any engineers who are interested in learning the syntax of different languages.