NEW! Master Swift design patterns with my latest book! >>

How to loop over non-nil items in an array

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.

Available from iOS – learn more in my book Pro Swift

Did this solution work for you? Please pass it on!

Other people are reading…

About the Swift Knowledge Base

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

Love Hacking with Swift?

Get all 40 projects in PDF and HTML: buy the Hacking with Swift book! It contains over 1300 pages of hands-on Swift coding, and will really help boost your iOS career

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>