Swift version: 5.6
The reduce()
method iterates over all items in array, combining them together somehow until you end up with a single value. The “somehow” is specified by a closure you provide, for example you might want to count how many characters are provided in an array of names, which looks like this:
let names = ["Taylor", "Paul", "Adele"]
let count = names.reduce(0) { $0 + $1.count }
print(count)
That starts with a total of 0 (the parameter passed in to reduce()
, then adds that to the count of each string in the array. So, it starts by adding 6 for Taylor (so the running total is 6), then adds 4 for Paul (so the running total is 10), then adds 5 more for Adele (so the running total is 15.)
SAVE 50% To celebrate WWDC23, 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.
Available from iOS – learn more in my book Pro Swift
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
Link copied to your pasteboard.