Get quick answers for developing and debugging applications with Swift, Apple's multi-paradigm programming language. This pocket reference is the perfect on-the-job tool for learning Swift's modern language features, including type safety, generics, type inference, closures, tuples, automatic memory management, and support for Unicode. Designed to work with Cocoa and Cocoa Touch, Swift can be used in tandem with Objective-C, and either of these languages can call APIs implemented in the other. Swift is still evolving, but it's clear that Apple sees it as the future language of choice for iOS and OS X software development. Topics include: Swift's Run-Eval-Print-Loop (REPL) and interactive playgrounds Supported data types, such as strings, arrays, and dictionaries Variables and constants Program flow: loops and conditional execution Classes, structures, enumerations, functions, and protocols Closures: similar to blocks in Objective-C and lambdas in C# Optionals: values that can explicitly have no value Operators, operator overloading, and custom operators Access control: restricting access to types, methods, and properties Built-in global functions and their parameter requirements