Chapter 02: Let’s Learn Swift Programming Language – Variables & Constants in Swift

Data Types in Swift Language

Integers i.e. Int: 1, 2, 3, 199, 1000
Float & Doubles: 3.14, 1.168, M_PI
Boolean Values like Bool: true or false
Collection of Characters like Strings: “iOS Development”, “Apple”, “1.2”
We can create our own data type using keywords Struct & Class.

All About Variables


Here is how we declare Variables in Swift: First we start with ‘var’ keyword then ‘Identifier Name’ & ‘Initial Value’

Here is how to Declare Integer values: Int

var thisYear = 2017
var ourAge = 20

Here is how to Declare Empty Integer

var emptyInteger = Int()

Here is how to Declare String

var courseName = "iOS Development"
var language = "Swift"
var software = "Xcode"

Here is how to Declare Empty String

var emptyString = String()

Here is how to Declare Double or Float

var currentSwiftVersion = 3.0

Here is how to Declare Empty Double or Floating point variable

var emptyDouble = Double()

Here is how to Declare Boolean Value: Bool

var programmingIsFun = true

Here is how to Declare Empty Boolean value

var emptyBoolean = Bool()


Important thing to remember: Swift compiler knows type of variable when you declare them as types of variables are inferred by compiler.


All About Constants: Value of constant never change & it will help you to protect that keyword from anyone changing that value.

Here is how declare Constants in Swift: You will start ‘Let’ Keyword then ‘Identifier name’ equal sign & Constant Value

Here is how to Declare Integer constant: Int

let thisYear = 2017
let ourAge = 20

Here is how to Declare String constant

let courseName = "iOS Development"
let language = "Swift"
let software = "Xcode"

Here is how to Declare Double or Float constant

let currentSwiftVersion = 3.0

All about Operators available in Swift Language that you can use.

Assignment Operator is ‘=’ which will help you to assign value to ‘identifier name’ for your keyword

Arithmetic Operators available in Swift
Addition Operator: ‘+’
Subtraction Operator: ‘-’
Multiplication Operator: ‘*’
Division Operator: ‘/’
Modulus Operator: ‘%’

Using Arithmetic Operators

var addition = 3 + 8 // Result is 11
var subtraction = addition - 10 // Result is 1, As addition value declared in above line is 11 then it subtract value 10 from addition value & assign it to subtraction keyword
subtraction = subtraction + 10 // Result is 11
subtraction += 5 // Result is 16


var division = 10 / 2 // Result is 5
var remainder = division % 5 // Result is 1

I hope This information helps you to get started with Swift Programming Language & clear all your doubts about data types, variable & constants.

Thanks & Regards
Mandar Apte

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