How to find the difference between two arrays
Swift version: 5.6
If you have two arrays that contain similar items and want to find out their differences – i.e., which items exist in one or the other, but not both – the easiest thing to do is use a Set. Sets have a symmetricDifference() method that does exactly this, so you just need to convert both arrays to a set, then convert the result back into an array.
Here’s an extension to make it easier:
extension Array where Element: Hashable {
func difference(from other: [Element]) -> [Element] {
let thisSet = Set(self)
let otherSet = Set(other)
return Array(thisSet.symmetricDifference(otherSet))
}
}And here’s some example code you can use to try it out:
let names1 = ["John", "Paul", "Ringo"]
let names2 = ["Ringo", "Paul", "George"]
let difference = names1.difference(from: names2)That will set difference to be ["George", "John"], because those are the two names that only appear once in either array.
SPONSORED 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! Hurry up because it'll be available only until April 28th.
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 8.0
Similar solutions…
- How to use the zip() function to join two arrays
- How to find the minimum of two numbers
- How to find the maximum of two numbers
- How to calculate the distance between two CGPoints
- How to calculate the Manhattan distance between two CGPoints
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
