# insert(_:) Inserts the given element in the set if it is not already present. ``` @discardableResult mutating func insert(_ newMember: Element) -> (inserted: Bool, memberAfterInsert: Element) ``` ## Parameters `newMember` An element to insert into the set. ## Return Value `(true, newMember)` if `newMember` was not contained in the set. If an element equal to `newMember` was already contained in the set, the method returns `(false, oldMember)`, where `oldMember` is the element that was equal to `newMember`. In some cases, `oldMember` 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, this method has no effect. In the following example, a new element is inserted into `classDays`, a set of days of the week. When an existing element is inserted, the `classDays` set does not change. ``` enum DayOfTheWeek: Int { case sunday, monday, tuesday, wednesday, thursday, friday, saturday } var classDays: Set = [.wednesday, .friday] print(classDays.insert(.monday)) // Prints "(inserted: true, memberAfterInsert: DayOfTheWeek.monday)" print(classDays) // Prints "[DayOfTheWeek.friday, DayOfTheWeek.wednesday, DayOfTheWeek.monday]" print(classDays.insert(.friday)) // Prints "(inserted: false, memberAfterInsert: DayOfTheWeek.friday)" print(classDays) // Prints "[DayOfTheWeek.friday, DayOfTheWeek.wednesday, 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)