Swift 3 is a major, breaking language change. Are you ready to make the jump? Let "Swift From Two to Three" help you along the way. From migrating your code, updating your style, and adopting new Swift features, this book ushers you into the newly refreshed language. Learn what changed, why it changed, and how you can update your code using this hands-on guide that covers all the major difference with plenty of examples and insight. 

Playgrounds offer an essential Swift learning, development, and documentation tool. They enable you to explore the Swift language, test out routines, prototype quick solutions, delve into Cocoa / Cocoa Touch APIs, and create flexible interactive documents. That's a lot of power for one minor Xcode feature and that's why this book exists. Playgrounds don't just let you tweak, test, and explore, they offer an exciting tool suite that promotes data visualization and design clarity.

Playgrounds provide instant gratification for every bit of code you type. Imagine creating fully operational code elements in just a few lines. APIs, functions, and methods spring to life, ready for testing and refinement. Apple has invested a lot of work into making these environments a fantastic touch point for language development support. If you think a playground is nothing more than a read-eval-print loop with pretentions, you're missing the point. Inline value previews, timeline exploration, rich documentation, and other highly visual elements support development beyond the level of "does this compile?" and "what value does this return?

"Playgrounds are so so great :) …reading “Playground Secrets and Power Tips” by @ericasadun" – Don Southard @dirtdon

"Trying to figure out the XCPlayground stuff, and I knew @ericasadun would have my back. Thanks!" – Laura Dickey, @littlepotatosw

"Just picked up Playground Secrets. Your books have always been a meaningful part of my learning and growth. Thank you!" – Zach Starkebaum, @rebelzach

"Xcode Playgrounds book by @ericasadun keeps being updated and getting better." – John Haney, @johnhaney

"Thanks for your amazing work Erica! Loved your book" – Jasdev Singh, @jasdev

"Purchased your Playgrounds book. It is invaluable, thank-you." – Russell Gordon, @rgordon

Nearly every modern language, including Swift, offers some kind of structured comment system that documents APIs for developers that consume them. The new Swift 2 structured documentation uses a mix of custom keywords and Markdown syntax to create a simple, easy-to-apply annotation tool. By leveraging this industry-standard tech, Apple opens up its structured documentation system to an entirely new generation with an absolute minimum of training needed to get up to speed.

This short book introduces Swift's documentation markup system using simple, illustrated examples, with plenty of discussion of best practices. You'll discover the components that make up Swift's structured comment system and learn how to best integrate them into your own code. For the most part, I've built this material out of examples from Swift's standard library, from release notes, and by reverse-engineering extensible style-sheet specifications. While I've tried to include a thorough list of legal tokens, I've focused on supplementing core details with a thoughtful discussion of best practices that will stand the test of time as Apple updates this system.

I hope you find this book to be a useful and worthy addition to your development library. I've had a great time writing it. Hopefully you'll have a great time reading it. Thank you for purchasing a copy!

Updates:

1.2 Added CommonMark update, updated playground section, added coverage of video embedding, added various tweaks and enhancements based on material found in Apple's open source content.

1.1.7 Added note about upcoming 7.3 Playground Doc keywords (experiment, note, and important) plus link to blog coverage.

1.1.6 Added coverage of Xcode 7.3/Swift 2.2's new keywords (recommended, recommendedover, keyword)

1.1.5 Expanded guidelines with Apple's updated API Design Guidelines document. There isn't a big difference beyond using "s" at the end of verbs when writing descriptions.

1.1.4 Added coverage of VVDocumenter's Xcode plug-in, updated Jazzy coverage

1.1.3 Errata fixes. Thank you Juan Diego.

1.1.2 Minor updates after Swift open sourced with API guidelines incorporated into a couple of discussions.

1.1.1 Added revision history (thanks, Adolofo Vera Blasco)

1.1.0 Major additions include expanded markup discussions, third party tool overviews, playground rich text documents: approximately 30% additional content.

1.0.1 Minor style fixes