Swift - Random Numbers

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Random Numbers are the sequence of numbers that are generated by the system without any pre-defined pattern or in an unpredictable manner. They are commonly used in chance events, produce unpredictable outcomes, etc. Random numbers are widely used in cryptography, gaming, statistical analysis, generating unique id/sessions for users, etc.

In Swift, we can find random numbers using the following methods −

  • random(in:) function
  • random(in: using:) function
  • randomElement() function

Using random(in:) Function

We can find random numbers with the help of the random(in:) function. This function returns a random number from the given range. Using this function, we can generate random numbers of Int, Double, Float and Bool types.

Syntax

Following is the syntax of the random(in:) function −

static func random(in: inputRange)

Here this function takes only one parameter which is the inputRange. The inputRange represents a range in which a random() function creates a random number.

Return Value

This function returns a random number from the given range.

Example

Swift program to generate random numbers using random(in:) function.

import Foundation

// Generating a random number of Int type
var randomNumber1 = Int.random(in: 10...23)
print("Random Number:", randomNumber1)

// Generating a random number of Float type
var randomNumber2 = Float.random(in: 10.2...23.2)
print("Random Number:", randomNumber2)

// Generating a random number of Double type
var randomNumber3 = Double.random(in: 15.2..<25.2)
print("Random Number:", randomNumber3)

// Generating a random number of Bool type
var randomNumber4 = Bool.random()
print("Random Number:", randomNumber4)

Output

It will produce the following output −

Random Number: 20
Random Number: 14.4035845
Random Number: 17.450544998301993
Random Number: true

Using random(in:using:) Function

To generate random numbers Swift supports a pre-defined function named random(in:using:) function. This function generates a random number within the given range with the help of a given generator. It also generates random numbers of Int, Double, Float and Bool types.

Syntax

Following is the syntax of the random(in:using:) function −

static func random(in: inputRange, using: generator)

This function takes two parameters −

  • inputRange − It represents a range. Its value must not be empty.

  • generator − It represents the generator using which random(in:using:) function will generate a random number.

Return Value

This function returns a random number within the specified range.

Example

Swift program to generate random numbers using random(in:using:) function.

import Foundation

// Specifying a generator
var myGenerator = SystemRandomNumberGenerator()

// Generating a random number of Int type
var randomNumber1 = Int.random(in: 30...43, using: &myGenerator)
print("Random Number:", randomNumber1)

// Generating a random number of Float type
var randomNumber2 = Float.random(in: 12.2...33.2, using: &myGenerator)
print("Random Number:", randomNumber2)

// Generating a random number of Double type
var randomNumber3 = Double.random(in: 35.2..<45.2, using: &myGenerator)
print("Random Number:", randomNumber3)

// Generating a random number of Bool type
var randomNumber4 = Bool.random(using: &myGenerator)
print("Random Number:", randomNumber4)

Output

It will produce the following output −

Random Number: 34
Random Number: 20.267605
Random Number: 42.47363754282583
Random Number: false

Using randomElement() Function

When we are working with collections such as an array and dictionary, we can use the randomElement() function. This function returns a random element from the given collection. The value returned by this function is an optional type so we must unwrap it using (!).

Syntax

Following is the syntax of the randomElement() function −

static func randomElement()

Return Value

This function returns a random number from the specified collection. If the collection is empty, then it will return nil.

Example

Swift program to generate a random element from the given collection.

import Foundation
let myVeggies = ["Lemon", "Cabbage", "Green Chilly", "Potato"]

// Getting random element
let randomVeggie = myVeggies.randomElement()!
print("Random Element: \(randomVeggie)")

Output

It will produce the following output −

Random Element: Lemon
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