Swift large body of existing Objective-C (ObjC) code
Swift is a general-purpose, multi-paradigm, compiled programming language developed by Apple Inc. for iOS, macOS, watchOS, tvOS, and Linux. Swift is designed to work with Apple’s Cocoa and Cocoa Touch frameworks and the large body of existing Objective-C (ObjC) code written for Apple products. It is built with the open source LLVM compiler framework and has been included in Xcode since version 6.
On platforms other than Linux,8 it uses the Objective-C runtime library which allows C, Objective-C, C++ and Swift code to run within one program.9Apple intended Swift to support many core concepts associated with Objective-C, notably dynamic dispatch, widespread late binding, extensible programming and similar features, but “safer” (easier to catch software bugs); Swift has features addressing some common programming errors like null pointers and provides syntactic sugar to help avoid the pyramid of doom. Swift supports the concept of protocol extensibility, an extensibility system that can be applied to types, structs and classes, which Apple promotes as a real change in programming paradigms they term “protocol-oriented programming”10 (similar to traits).11Swift was introduced at Apple’s 2014 Worldwide Developers Conference (WWDC).
12 It underwent an upgrade to version 1.2 during 2014 and a more major upgrade to Swift 2 at WWDC 2015. Initially a proprietary language, version 2.2 was made open-source software under the Apache License 2.0 on December 3, 2015, for Apple’s platforms and Linux.1314In March 2017, Swift made the top 10 in the monthly TIOBE index ranking of popular programming languages,15 and was ranked 11th at the end of 2017.16