NEW: Join my free 100 Days of SwiftUI challenge today! >>

How to group arrays using dictionaries

Swift version: 5.1

Paul Hudson    @twostraws   

If you have an array of items and want to group them according to some criteria, Swift has a special dictionary initializer just for you.

Here’s an example sequence we can work with:

let singers = ["Ed Sheeran", "Ariana Grande", "Taylor Swift", "Adele Adkins"]

We can now create a dictionary that groups those singers together by the length of their names:

let groupedByLength = Dictionary(grouping: singers) { $0.count }

That will put Taylor and Adele into an array under the “12” key, Ariana under 13, and Ed under 10.

Alternatively, we could group them by the first letters of each of their names:

let groupedByFirst = Dictionary(grouping: singers) { $0.first! }

LEARN SWIFTUI FOR FREE I have a massive, free SwiftUI video collection on YouTube teaching you how to build complete apps with SwiftUI – check it out!

Available from iOS 8.0 – learn more in my book Pro Swift

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 5.0/5