🐦 Swift

What is Swift?

Lesson 1 of 5 ~5 min

Swift is Apple's modern, powerful programming language used to build apps for iOS, macOS, watchOS, and tvOS. It's designed to be safe, fast, and expressive — making it the go-to language for Apple platform development.

Archon is built entirely in Swift. Learning Swift is the first step toward understanding how your app works under the hood.

Why Swift?

→ Type safe — Swift catches type errors at compile time, preventing many common bugs before your code ever runs.
→ Modern syntax — Clean and readable, making it easier to write and maintain code.
→ Performance — Compiled language that runs fast, comparable to C++.
→ Interoperable — Works seamlessly with existing Objective-C code.

Constants and Variables

Swift uses let for constants and var for variables. Constants are values that never change — and Swift encourages you to use them whenever possible.

Editor

Swift

// Constants (can't be changed)
let name = "Archon"
let version = 2.0

// Variables (can be changed)
var downloads = 100
downloads = 150

// String interpolation
print("App: \(name) v\(version)")
print("Downloads: \(downloads)")

// Basic types
let isActive: Bool = true
let count: Int = 42
let pi: Double = 3.14159
let greeting: String = "Hello, Swift!"

Output

Try it

Change the value of name and downloads in the editor. Notice how string interpolation with \() embeds values directly into strings.

Basic Types

// Strings — text values
let city = "San Francisco"

// Integers — whole numbers
let age = 28

// Doubles — decimal numbers
let temperature = 72.5

// Booleans — true or false
let isLoggedIn = true

// Type annotations (explicit types)
let population: Int = 850_000
let rating: Double = 4.8

Quiz

Which keyword declares a constant in Swift?

Challenge

Create constants for your name and age, then print them with string interpolation using \().

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