What is the difference between a set and a dictionary in Swift?

A Set stores an unordered collection of unique values of a single type. A Dictionary stores an unordered collection of key-value pairs, where keys are unique.

Main differences:

• Uniqueness of elements: Sets contain only unique elements. Dictionaries have unique keys, but values can repeat.
• Structure: A Set stores individual elements. A Dictionary stores key-value pairs.
• Access to elements: In a Set, access to elements is done through iteration or checking for presence. In a Dictionary, access to values is done via the key.

Examples:

// Set
var uniqueNumbers: Set<Int> = [1, 2, 3, 1, 4] // Will store only [1, 2, 3, 4]

// Dictionary
var userAges: [String: Int] = ["Alice": 30, "Bob": 25, "Alice": 31] // "Alice" will have the value 31