How do you define a constant in Swift iOS?

2 min 19 sec read

Author: Manish Methani

A constant is an entity that doesn’t change whereas a variable is an entity that may change.

For example, when we write

int a = 10
int a = 20
int a = 30

'a' is variable & '10' is constant. Variable 'a' value can be changed to '20' or '30' but you cannot change '10' or '20' or '30' . These are constant values . They are just the numbers.

Constant Declaration in Swift :

To declare constants in Swift 'let' keyword is used. Semicolons are not compulsory in Swift Language. But remember if you add two statements in a single line you have to use ';' as delimiter to separate them. Otherwise, it shows syntax error.

Syntax :-

let constantName = Constant Value

Example :-

let name = "Manish"
let a = 20
let b = 20.0

Let's create a sample playground , Goto File > New > Playground > Next.


import UIKit
let a = 20

Run the program in the playground.



Type Annotations

Annotations are used to specify the type to constant. With the help of Type Annotations it will be clear what kind of value that specific constant can store. And this can be done by placing a colon after the constant or variable name, followed by a space, followed by the name of the type to use.


let constantName:type = value

Example :-

import UIKit
let name: String
name = "Manish"

let varA:Float = 30.0

Output :-


Print in Swift 3.1

//: Playground - noun: a place where people can play

import UIKit

let name = "Manish"
var age = 23

print("(name) age is = (age)")


Manish age is = 23

How was the tutorial? Nice. Right?

Deep Concept videos to crack the highly-piad interviews.

Chekout out our Youtube Channel to get detailed video content on important topics in interviews.

What is your Interview Score?

Test your skillset with the curated questions created by experts around the globe.

Book a free test slot. Now !.

It usually takes 30 mins for an online test and this test will be MCQ based. Get detailed analytics based on your test and recommedations with personalised roadmaps.

Book a test slot. Now!

Have questions about the trial coding class?

Chat with our experts to discuss

Connect on WhatsApp

Recommended tutorials

#online compiler for c     #python for programming    

#dfs and bfs algorithm     #programming with c language

#storageclass in C    #listcomprehension in python