Swift Quick Syntax Reference

Chapter    2

Declaring Constants and Variables

While you can use values like the string "Hello World" from the previous chapter or a number like 3.14 directly in code, usually you assign values like these to either a variable or a constant. You can give values a convenient name using variables and constants in Swift.

Variables can change their values over time, while constants get an assigned value and keep that value throughout the execution of a program. Both variables and constants can store only one type of data.

Constants

Let’s reproduce the Hello World example from Chapter 1 using a constant. Listing 2-1 shows how to store the string "Hello World" in a constant named s1.

Listing 2-1. Hello World Constant

let s1:String = "Hello World"