How to loop over non-nil items in an array
Swift version: 5.4
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 Join a FREE crash course for iOS devs who want to become complete senior developers — from October 18th to 24th. Learn how to apply iOS app architecture patterns through a series of lectures and practical coding sessions.
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 loop through an array in reverse
- How to detect the user hovering over a view
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
