This tutorial belongs to the Swift series

Sets are used to create collections of non-repeated items.

While an array can contain many times the same item, you only have unique items in a set.

You can declare a set of Int values in this way:

`let set: Set<Int> = [1, 2, 3]`

or you can initialize it from an array:

`let set = Set([1, 2, 3])`

Add items to the set using `insert()`

:

```
var set = Set([1, 2, 3])
set.insert(17)
```

Unlike arrays, there is no order or position in a set. Items are retrieved and inserted randomly.

The way to print the content of a set ordered is to transform it into an array using the `sorted()`

method:

```
var set = Set([2, 1, 3])
let orderedList = set.sorted()
```

To check if a set contains an element, use the `contains()`

method:

```
var set = Set([1, 2, 3])
set.contains(2) //true
```

To get the number of items in the set, use the `count`

property:

```
let set = Set([1, 2, 3])
set.count //3
```

If a set is empty, its `isEmpty`

property is `true`

.

```
let set = Set([1, 2, 3])
set.isEmpty //false
```

To remove one item from the array, use `remove()`

passing the value of the element:

```
var set = Set([1, 2, 3])
set.remove(1)
//set is [2, 3]
```

To remove all items from the set, you can use removeAll():

`set.removeAll()`

Sets, like arrays, are passed by value, which means if you pass it to a function, or return it from a function, the set is copied.

Sets are great to perform set math operations like intersection, union, subtracting, and more.

These methods help with this:

`intersection(_:)`

`symmetricDifference(_:)`

`union(_:)`

`subtracting(_:)`

`isSubset(of:)`

`isSuperset(of:)`

`isStrictSubset(of:)`

`isStrictSuperset(of:)`

`isDisjoint(with:)`

Sets are collections, and they can be iterated over in loops.