NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

How to loop over non-nil items in an array

Swift version: 5.2

Paul Hudson    @twostraws   

Consider an array of items containing some optionals, like this one:

let numbers: [Int?] = [1, nil, 3, nil, 5]

If you want to loop over all the items and print them out, you’d write something like this:

for number in numbers {
    print(number)
}

However, that prints out all items in their current state: optionally wrapped integers for some, nil for others.

With a small change to that loop, you can have Swift unwrap all the optionals then only enter the loop for any that contain a value – any nil items are ignored. This is done using for case let syntax, like this:

for case let number? in numbers {
    print(number)
}

That will print the numbers 1, 3, and 5.

Hacking with Swift is sponsored by Instabug

SPONSORED Are you tired of wasting time debugging your Swift app? Instabug’s SDK is here to help you minimize debugging time by providing you with complete device details, network logs, and reproduction steps with every bug report. All data is attached automatically, and it only takes a line of code to setup. Start your free trial now and get 3 months off exclusively for the Hacking with Swift Community.

Start your free trial!

Sponsor Hacking with Swift and reach the world's largest Swift community!

Available from iOS – 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

Link copied to your pasteboard.