update(with:)
Inserts the given element into the set unconditionally.
Declaration
@discardableResult mutating func update(with newMember: Self.Element) -> Self.Element?Parameters
- newMember:
An element to insert into the set.
Return Value
For ordinary sets, 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.
For sets where the set type and element type are the same, like OptionSet types, this method returns any intersection between the set and [newMember], or nil if the intersection is empty.
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<DayOfTheWeek> = [.monday, .wednesday, .friday]
print(classDays.update(with: .monday))
// Prints "Optional(.monday)"