How to find the index of the first matching array element
Swift version: 5.6
If you have an array of items and want to find the first item that matches a specific condition, you should use the index(where:) method. This accepts a closure of code to use as a test, applies that test to all elements in an array, then returns the index of the first item to match it. If no item matches you’ll get back nil, so be prepared to unwrap the optional you get sent back.
For example, if we had an array of numbers:
let numbers = [2, 4, 6, 8, 9, 10]We could find the first odd number like this:
let firstOdd = numbers.index { $0 % 2 == 1 }That will send back 4 as an optional integer, because the first odd number (9) is at index four.
SPONSORED From March 20th to 26th, you can join a FREE crash course for mid/senior iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a complete senior developer!
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 8.0
Similar solutions…
- How to find the first matching element in an array
- How to count element frequencies in an array
- How to get a random element from an array using randomElement()
- How to count matching items in an array
- How to remove the first or last item from an array
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
