# formSymmetricDifference(_:) Replace this set with the elements contained in this set or the given set, but not both. ``` mutating func formSymmetricDifference(_ other: S) where Element == S.Element, S : Sequence ``` ## Parameters `other` A sequence of elements. `other` must be finite. ## Discussion In the following example, the elements of the `employees` set that are also members of `neighbors` are removed from `employees`, while the elements of `neighbors` that are not members of `employees` are added to `employees`. In particular, the names `"Bethany"` and `"Eric"` are removed from `employees` while the name `"Forlani"` is added. ``` var employees: Set = ["Alicia", "Bethany", "Diana", "Eric"] let neighbors = ["Bethany", "Eric", "Forlani"] employees.formSymmetricDifference(neighbors) print(employees) // Prints "["Diana", "Forlani", "Alicia"]" ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)