Swift Tutorial - Swift Data Types

The following table describes the common Swift data types.

Data TypeDescription
StringSequence of characters
IntWhole number
FloatNumber with fractional component
DoubleBigger number with fractional component
BoolTrue or false value


The following code how to use these data types.

let s:String = "Hey There"
let i:Int = -5
let f:Float = 3.14
let d:Double = 9.9
let b:Bool = true

Type Inference

Swift compiler can figure data type out based on what value you assign to the variable or constant. This is called type inference.

This means you could have omitted the :String from your declarations and instead use something as follows.

var s3 = "java2s.com"

Printing Variables and Constants

The following code uses the println function to output string to console.

import Foundation
println("Hello, World!")

The following code shows how to print Variables.

import Foundation
let s:String = "Hey There"

println() prints something out and then goes to the next line, print() will print out a value without moving to the next line in the console window.

import Foundation
print("Print this")
print(" and ")

Swift Type Aliases

We can add an alternative name for existing types using type aliases.

The following code uses a type alias to define Note as an alternative to String.

typealias Note = String
var n1:Note = "hi"

You can treat n1 as a string.