Getting Started

Swift Introduction

Get started with Swift — Apple's powerful, safe, and expressive language for iOS and macOS.

What is Swift?

Swift is a general-purpose programming language developed by Apple. It is the primary language for developing apps for iOS, macOS, watchOS, and tvOS. Swift is also available on Linux and Windows.

Key Features

  • Safe: Designed to prevent common programming errors (null safety, type safety)
  • Fast: Performance comparable to C
  • Modern: Clean syntax with closures, generics, tuples
  • Expressive: Protocol-oriented programming, property wrappers
  • Open source: Available at swift.org

Swift vs Objective-C

Swift replaced Objective-C as Apple's primary language. Swift is:

  • Easier to read and write
  • Safer (optional types prevent null crashes)
  • More expressive
  • Interoperable with Objective-C

Getting Started

On macOS: install Xcode from the App Store. You can also use Swift Playgrounds or online playgrounds at swift.apple.com.

Example

swift
// Hello World in Swift
print("Hello, Swift!")

// Constants and variables
let name = "Swift"         // let = constant (immutable)
var version = 5.9          // var = variable (mutable)
// name = "Other"          // Error! Constants can't change
version = 6.0              // Fine

// Type annotations
let city: String = "London"
var count: Int = 0
var price: Double = 9.99
var isActive: Bool = true

// Type inference (Swift infers the type)
let language = "Swift"    // inferred as String
let pi = 3.14159          // inferred as Double

// String interpolation
print("Hello, \(name) \(version)!")
print("Pi is approximately \(pi)")

// Multi-line strings
let poem = """
Roses are red,
Violets are blue,
Swift is awesome,
And so are you!
"""
print(poem)
Try it yourself — SWIFT