Swift Syntax

Swift Syntax

Learn Swift basics: variables, types, string interpolation, and simple functions.

Basics

Lets look at some basic Swift syntax:

• Constants/variables: Use let (constant) and var (variable).
• Types: Common types include Int, Double, Bool, String.
• Type inference: The compiler infers types from initial values.

let greeting = "Hello"
var name = "Swift"
print(greeting + ", " + name)

let pi: Double = 3.14159
var count: Int = 3
print("pi = \(pi), count = \(count)")

Example explained

• let creates an immutable constant; var creates a mutable variable.
• Type annotation is optional; here we annotate Double and Int.
• String interpolation: \(expr) inserts values into strings.

String Interpolation

String interpolation is a way to embed expressions inside string literals for formatting.

In swift string interpolation is done using \(expr).

The most common and simple way to use string interpolation is to embed variable names inside string literals.

let greeting = "Hello"
var name = "Swift"
print("\(greeting), \(name)!")

Functions

Functions are blocks of code that perform a specific task.

Syntax: func name(param: Type) -> Return, call as name(param:).

func add(_ a: Int, _ b: Int) -> Int {
  return a + b
}
print(add(2, 3))  // 5

This example defines add with two Int parameters and returns their sum as Int.

Functions will be covered in detail in the Functions chapter.