The power of map in Swift

Uplift iOS Interview

"Uplift iOS Interview" is a comprehensive guide to help aspiring iOS developers soar to new heights in their careers. This book is an indispensable tool for anyone looking to crack the iOS interview and impress their future employers with their technical prowess. With in-depth coverage of Swift, AutoLayout, SwiftUI, Multithreading, Memory management so on and so forth, this book is a treasure trove of knowledge for anyone looking to uplift their iOS development career.

The map function in Swift is a powerful tool for transforming the elements of a collection in a concise and expressive way. It allows you to apply a specific operation to each element of a collection, such as converting an array of integers to an array of strings, or doubling the values in an array of numbers.

The map function takes one argument, a closure that specifies the transformation to be applied to each element of the collection. The closure takes one argument, the current element being processed, and returns a new value, which becomes the corresponding element in the new collection.

For example, if you have an array of integers and you want to double the values in the array, you could use the map function like this:

let numbers = [1, 2, 3, 4, 5]
let doubledNumbers = numbers.map { $0 * 2 }
print(doubledNumbers) // prints [2, 4, 6, 8, 10]

In this case, the closure is { $0 * 2 }, which takes a single argument, an integer, and returns its double. The map function applies this closure to each element of the numbers array, creating a new array that contains the doubled values.

Another example, we could use the map function to convert an array of integers to an array of strings, like this:

let numbers = [1, 2, 3, 4, 5]
let strings = numbers.map { String($0) }
print(strings) // prints ["1", "2", "3", "4", "5"]

In this example, the closure is { String($0) }, which takes a single argument, an integer, and returns its string representation. The map function applies this closure to each element of the numbers array, creating a new array that contains the string representations of the integers.

We can also use map function to transform array of custom objects to new custom objects, let’s say we have a custom object Person and we want to create an array of Person ages.

struct Person {
    let name: String
    let age: Int
}
let people = [Person(name: "John", age: 30), Person(name: "Jessica", age: 25)]
let ages = people.map { $0.age }
print(ages) // prints [30, 25]

The map function is a powerful tool for transforming collections in a concise and expressive way. It allows you to apply a specific operation to each element of a collection and create a new collection with the results, without the need for explicit loops or mutable variables. This makes it an excellent choice for functional programming, and for situations where you need to perform a simple, one-time transformation of a collection.


Rev Up Your iOS Skills: Take a Dynamic Learning Journey
iOS Career Boost

iOS Career Boost is the ultimate learning journey to elevate your iOS development career through a dynamic blend of visual learning, handy cheat sheets, coding practice materials, and expertly curated tips and tricks


Get Ready to Shine: Mastering the iOS Interview


Enjoying the articles? Get the inside scoop by subscribing to my newsletter.

Get access to exclusive iOS development tips, tricks, and insights when you subscribe to my newsletter. You'll also receive links to new articles, app development ideas, and an interview preparation mini book. Your email address will only be used for the purpose of sending the newsletter and will not be shared with third parties or advertisers. Rest assured that we value your privacy and will not spam your inbox.


Connect with me on

Twitter and LinkedIn and don't hesitate to reach out with any questions about this post. Thank you for reading.

If you know someone who would benefit from reading this article, please share it with them.