CustomValueOptionSet

Provides a text value description for user-provided options.

The option set will recognize a custom option if it’s unique rawValue flag is set and customOptionsByRawValue contains a description for that flag. Use the update(customOption:comparisonPolicy:) method to append a custom option.

Returns a Boolean value that indicates whether the given element exists in the set.

This example uses the contains(_:) method to test whether an integer is a member of a set of prime numbers.

let primes: Set = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37]
let x = 5
if primes.contains(x) {
    print("\(x) is prime!")
} else {
    print("\(x). Not prime.")
}
// Prints "5 is prime!"

Returns a new set with the elements of both this and the given set.

In the following example, the attendeesAndVisitors set is made up of the elements of the attendees and visitors sets:

let attendees: Set = ["Alicia", "Bethany", "Diana"]
let visitors = ["Marcia", "Nathaniel"]
let attendeesAndVisitors = attendees.union(visitors)
print(attendeesAndVisitors)
// Prints "["Diana", "Nathaniel", "Bethany", "Alicia", "Marcia"]"

If the set already contains one or more elements that are also in other, the existing members are kept.

let initialIndices = Set(0..<5)
let expandedIndices = initialIndices.union([2, 3, 6, 7])
print(expandedIndices)
// Prints "[2, 4, 6, 7, 0, 1, 3]"

Adds the elements of the given set to the set.

In the following example, the elements of the visitors set are added to the attendees set:

var attendees: Set = ["Alicia", "Bethany", "Diana"]
let visitors: Set = ["Diana", "Marcia", "Nathaniel"]
attendees.formUnion(visitors)
print(attendees)
// Prints "["Diana", "Nathaniel", "Bethany", "Alicia", "Marcia"]"

If the set already contains one or more elements that are also in other, the existing members are kept.

var initialIndices = Set(0..<5)
initialIndices.formUnion([2, 3, 6, 7])
print(initialIndices)
// Prints "[2, 4, 6, 7, 0, 1, 3]"

Returns a new set with the elements that are common to both this set and the given set.

In the following example, the bothNeighborsAndEmployees set is made up of the elements that are in both the employees and neighbors sets. Elements that are in only one or the other are left out of the result of the intersection.

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let neighbors: Set = ["Bethany", "Eric", "Forlani", "Greta"]
let bothNeighborsAndEmployees = employees.intersection(neighbors)
print(bothNeighborsAndEmployees)
// Prints "["Bethany", "Eric"]"

Removes the elements of this set that aren’t also in the given set.

In the following example, the elements of the employees set that are not also members of the neighbors set are removed. In particular, the names "Alicia", "Chris", and "Diana" are removed.

var employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let neighbors: Set = ["Bethany", "Eric", "Forlani", "Greta"]
employees.formIntersection(neighbors)
print(employees)
// Prints "["Bethany", "Eric"]"

Returns a new set with the elements that are either in this set or in the given set, but not in both.

In the following example, the eitherNeighborsOrEmployees set is made up of the elements of the employees and neighbors sets that are not in both employees and neighbors. In particular, the names "Bethany" and "Eric" do not appear in eitherNeighborsOrEmployees.

let employees: Set = ["Alicia", "Bethany", "Diana", "Eric"]
let neighbors: Set = ["Bethany", "Eric", "Forlani"]
let eitherNeighborsOrEmployees = employees.symmetricDifference(neighbors)
print(eitherNeighborsOrEmployees)
// Prints "["Diana", "Forlani", "Alicia"]"

Removes the elements of the set that are also in the given set and adds the members of the given set that are not already in the set.

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: Set = ["Bethany", "Eric", "Forlani"]
employees.formSymmetricDifference(neighbors)
print(employees)
// Prints "["Diana", "Forlani", "Alicia"]"

Returns a new set containing the elements of this set that do not occur in the given set.

In the following example, the nonNeighbors set is made up of the elements of the employees set that are not elements of neighbors:

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let neighbors: Set = ["Bethany", "Eric", "Forlani", "Greta"]
let nonNeighbors = employees.subtracting(neighbors)
print(nonNeighbors)
// Prints "["Diana", "Chris", "Alicia"]"

Removes the elements of the given set from this set.

In the following example, the elements of the employees set that are also members of the neighbors set are removed. In particular, the names "Bethany" and "Eric" are removed from employees.

var employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let neighbors: Set = ["Bethany", "Eric", "Forlani", "Greta"]
employees.subtract(neighbors)
print(employees)
// Prints "["Diana", "Chris", "Alicia"]"

Inserts the given element in the set if it is not already present.

If an element equal to newMember is already contained in the set, this method has no effect. In this 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<DayOfTheWeek> = [.wednesday, .friday]
print(classDays.insert(.monday))
// Prints "(true, .monday)"
print(classDays)
// Prints "[.friday, .wednesday, .monday]"

print(classDays.insert(.friday))
// Prints "(false, .friday)"
print(classDays)
// Prints "[.friday, .wednesday, .monday]"

Removes the given element and any elements subsumed by the given element.

For sets where the set type and element type are the same, like OptionSet types, this method returns any intersection between the set and [member], or nil if the intersection is empty.

Inserts the given element into the set unconditionally.

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)"

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.

Inserts the given element into the set unconditionally.

If an element equal to customOption is already contained in the set, customOption replaces the existing element. Otherwise - updates the set contents and fills customOptionsByRawValue accordingly.

For sets where the set type and element type are the same, like OptionSet types, this method returns any intersection between the set and [customOption], or nil if the intersection is empty.

Returns a Boolean value that indicates whether the set is a subset of another set.

Set A is a subset of another set B if every member of A is also a member of B.

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let attendees: Set = ["Alicia", "Bethany", "Diana"]
print(attendees.isSubset(of: employees))
// Prints "true"

Returns a Boolean value that indicates whether the set is a superset of the given set.

Set A is a superset of another set B if every member of B is also a member of A.

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let attendees: Set = ["Alicia", "Bethany", "Diana"]
print(employees.isSuperset(of: attendees))
// Prints "true"

Returns a Boolean value that indicates whether this set is a strict subset of the given set.

Set A is a strict subset of another set B if every member of A is also a member of B and B contains at least one element that is not a member of A.

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let attendees: Set = ["Alicia", "Bethany", "Diana"]
print(attendees.isStrictSubset(of: employees))
// Prints "true"

// A set is never a strict subset of itself:
print(attendees.isStrictSubset(of: attendees))
// Prints "false"

Returns a Boolean value that indicates whether this set is a strict superset of the given set.

Set A is a strict superset of another set B if every member of B is also a member of A and A contains at least one element that is not a member of B.

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let attendees: Set = ["Alicia", "Bethany", "Diana"]
print(employees.isStrictSuperset(of: attendees))
// Prints "true"

// A set is never a strict superset of itself:
print(employees.isStrictSuperset(of: employees))
// Prints "false"

Returns a Boolean value that indicates whether the set has no members in common with the given set.

In the following example, the employees set is disjoint with the visitors set because no name appears in both sets.

let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
let visitors: Set = ["Marcia", "Nathaniel", "Olivia"]
print(employees.isDisjoint(with: visitors))
// Prints "true"