Swift From Two to Three
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Swift From Two to Three

About the Book

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. 

About the Author

erica sadun
erica sadun

Erica Sadun writes lots of books. When not writing, she's a full time parent of geeks who are brushing up on their world domination skills. According to her academic dosimeter, she's acquired more education than any self-respecting person might consider wise. She enjoys deep diving into technology and has written, co-written, and contributed to dozens of books about computing and digital media. Sadun has blogged at TUAW, Ars Technica, O'Reilly, and Lifehacker. If you have any comments or questions about her ebooks, please drop an email at erica@ericasadun.com. Follow the author on her blog and Twitter (@ericasadun) to keep up with news and ebook announcements

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Table of Contents


  • Swift's Background
  • An Evolving Language
  • From 2 to 3
  • Swift History
  • Denial, Anger, Bargaining, and Acceptance
  • Learning Swift


  • How to Migrate
  • Swift 2.3 and Swift 3.0
  • Migration Lessons

Swift 2 to 3

  • Access Control
  • Open Access for Classes
  • First Parameter Argument Labels
  • Default Parameter Order
  • Removing Argument Labels from Types
  • Required Parameter Parentheses
  • Improved Operator Precedence
  • Operator Implementations in Types
  • Operator and Comment Interaction
  • Updated Conditions
  • Moving Generic `where` Clauses
  • Declaring Compound Protocols
  • Generic Type Aliases
  • Keyword-named Members

Cocoa Interop

  • Automated Framework API Changes
  • API Pruning
  • Imported Boolean Properties
  • Imported APIs and Default Arguments
  • Structural Import Changes
  • Importing Objective-C `id`
  • Errors and NSError
  • Abolishing the ImplicitlyUnwrappedOptional Type
  • Hoisting
  • Explicit Bridging Conversions
  • Objective-C Options and Constants
  • Property Selectors
  • Key Paths
  • Other Import Changes

Standard Library and Swift Foundation

  • API Guidelines
  • Lower Case Enumerations for Apple APIs
  • Swift Foundation Value Types
  • Inspecting Values and Types
  • Pointer Nullability
  • Accessing Raw Untyped Memory
  • The Never Type
  • New Sequence Functions
  • Removing Optional Comparisons
  • Building Strings from UTF8 Units
  • Indexing Collections
  • Dispatch
  • Standard Library API Changes

Swift 2 to Swift 2.3

  • For Loops, Increments and Decrements
  • Associated Types
  • Compile Time Version Checks
  • Eliminating parameter backticks
  • Compile-time Selectors Checks
  • Naming Functions with Argument Labels
  • Tuple Comparisons
  • Goodbye to Tuple Splat
  • Var Parameter Deprecation
  • Redesigning Currying
  • Debug identifiers are renamed
  • Dot Operators
  • Upgrading AnyGenerator
  • And more…

Swift 3 to 3.1

  • Adding `prefix(while:)` and `drop(while:)` to the Standard Library

Major Swift 3 and 4 announcements

  • Swift 3.0 Release Process
  • Swift ABI Stability Deferred
  • Swift 3 Endgame and Swift 4 Kickoff
  • Ending Swift 3 Source Breaking Changes
  • Wrapping up Swift 3 and starting Swift 4

Revision History

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