# update(with:) Inserts the given element into the set unconditionally. ``` @discardableResult mutating func update(with newMember: Element) -> Element? ``` ## Parameters `newMember` An element to insert into the set. ## Return Value An element equal to `newMember` if the set already contained such a member; otherwise, `nil`. In some cases, the returned element may be distinguishable from `newMember` by identity comparison or some other means. ## Discussion If an element equal to `newMember` is already contained in the set, `newMember` replaces the existing element. In this example, an existing element is inserted into `classDays`, a set of days of the week. ``` enum DayOfTheWeek: Int { case sunday, monday, tuesday, wednesday, thursday, friday, saturday } var classDays: Set = [.monday, .wednesday, .friday] print(classDays.update(with: .monday)) // Prints "Optional(DayOfTheWeek.monday)" ``` --- 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)