.intersection()

The .intersection() method returns a new set containing all elements of the set that also belong to the given sequence.

newSet = mySet.intersection(mySequence)

Sets mySet and sequence mySequence must have a countable number of members.

let friends: Set = ["Pam", "Jim", "Andy", "Darryl"]
let colleagues = ["Dwight", "Michael", "Kelly", "Andy", "Darryl"]
let workFriends = friends.intersection(colleagues)
print(workFriends)

let groupAges: Set = [12, 22, 17, 45, 64, 6]
let minorAges = (0...17)
let children = groupAges.intersection(minorAges)
print(children)

This will output:

["Darryl", "Andy"]
[17, 6, 12]

Note: A set is an unordered data structure, so elements may be ordered differently when outputted.