Swift

3.2    Sets

In Swift, a set is a collection, like an array; they share some common ground. The core difference is that a set is an unordered collection of unique values. Unlike arrays, sets don’t allow duplicate elements and don’t guarantee a specific order by index—but they promise a very high access speed, which is a significant benefit in large datasets.

Table 3.12 describes the differences between arrays and sets clearly.

Feature	Array	Set
Order	Ordered	Unordered
Duplicate values	Allowed	Not allowed
Access by index	Allowed	Not allowed
Element lookup speed	Slow	Fast

Table 3.12     Comparison Between Arrays and Sets

The selling points of a set are basically element uniqueness and access speed. ...