WWDC24 SALE: Save 50% on all my Swift books and bundles! >>

count(where:)

Available from Swift 6.0

Paul Hudson      @twostraws

SE-0220 introduced a new count(where:) method that performs the equivalent of a filter() and count in a single pass. This saves the creation of a new array that gets immediately discarded, and provides a clear and concise solution to a common problem.

This example creates an array of test results, and counts how many are greater or equal to 85:

let scores = [100, 80, 85]
let passCount = scores.count { $0 >= 85 }

And this counts how many names in an array start with “Terry”:

let pythons = ["Eric Idle", "Graham Chapman", "John Cleese", "Michael Palin", "Terry Gilliam", "Terry Jones"]
let terryCount = pythons.count { $0.hasPrefix("Terry") }

This method is available to all types that conform to Sequence, so you can use it on sets and dictionaries too.

Note: count(where:) was originally planned for Swift 5.0 way back in 2019, but was withdrawn at the time for performance reasons.

Save 50% in my WWDC sale.

SAVE 50% To celebrate WWDC24, all our books and bundles are half price, so you can take your Swift knowledge further without spending big! Get the Swift Power Pack to build your iOS career faster, get the Swift Platform Pack to builds apps for macOS, watchOS, and beyond, or get the Swift Plus Pack to learn advanced design patterns, testing skills, and more.

Save 50% on all our books and bundles!

Other changes in Swift 6.0…

Download all Swift 6.0 changes as a playground Link to Swift 6.0 changes

Browse changes in all Swift versions

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.