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Swift - Introduction

Swift is a general-purpose, multi-paradigm, compiled programming language developed by Apple Inc. and the open-source community. It was first released in 2014 as a replacement for Apple's earlier programming language Objective-C, as Objective-C had been largely unchanged since the early 1980s and lacked modern language features. It is built with the open source LLVM compiler framework and has been included in Xcode since version 6, released in 2014.

Language Features

Swift includes features that make code easier to read and write, while giving the developer the control needed in a true systems programming language. Swift supports inferred types to make code cleaner and less prone to mistakes, and modules eliminate headers and provide namespaces. Memory is managed automatically, and the user don't even need to type semi-colons. Swift also borrows from other languages, for instance named parameters brought forward from Objective-C are expressed in a clean syntax that makes APIs in Swift easy to read and maintain.

The features of Swift are designed to work together to create a language that is powerful, yet fun to use. Some additional features of Swift include:

  • Closures unified with function pointers
  • Tuples and multiple return values
  • Generics
  • Fast and concise iteration over a range or collection
  • Structs that support methods, extensions, and protocols
  • Functional programming patterns, e.g., map and filter
  • Powerful error handling built-in
  • Advanced control flow with do, guard, defer, and repeat keywords


Swift was designed from the outset to be safer than C-based languages, and eliminates entire classes of unsafe code. Variables are always initialized before use, arrays and integers are checked for overflow, and memory is managed automatically. Syntax is tuned to make it easy to define your intent — for example, simple three-character keywords define a variable (var) or constant (let).

Another safety feature is that by default Swift objects can never be nil, and trying to make or use a nil object results in a compile-time error. This makes writing code much cleaner and safer, and prevents a common cause of runtime crashes. However, there are cases where nil is appropriate, and for these situations Swift has an innovative feature known as optionals. An optional may contain nil, but Swift syntax forces you to safely deal with it using ? to indicate to the compiler you understand the behavior and will handle it safely.