How to use reduce() to condense an array into a single value
Swift version: 5.1
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 20% ON iOS CONF SG The largest iOS conference in Southeast Asia is back in Singapore for the 5th time in January 2020, now with two days of workshops plus two days of talks on SwiftUI, Combine, GraphQL, and more! Save a massive 20% on your tickets by clicking on this link.
Available from iOS – learn more in my book Pro Swift
Similar solutions…
- How to join an array of strings into a single string
- How to convert a multidimensional array to a single-dimensional array
- How to sum an array of numbers using reduce()
- How to detect the Reduce Motion accessibility setting
- How to read a single character from a string
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
