How to loop over non-nil items in an array

Swift version: 5.10

Paul Hudson    @twostraws    May 28th 2019

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.

SPONSORED Get accurate app localizations in minutes using AI. Choose your languages & receive translations for 40+ markets!

Localize My App

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

Available from iOS – learn more in my book Pro Swift

Similar solutions…

• How to use the forEach method to loop over an array
• Using stride() to loop over a range of numbers
• How to loop through items in an array
• How to detect the user hovering over a view
• How to modify haptic events over time using CHHapticParameterCurve

About the Swift Knowledge Base

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