Use Hashable Protocol in Swift

Written by Team Kodeco

The Hashable protocol in Swift provides a way to define an object as hashable, which means it can be used as the key in a dictionary or as an element in a set.

Here is an example implementation of the Hashable protocol in a custom data type Person:

struct Person: Hashable {
  let firstName: String
  let lastName: String
  let age: Int
  
  func hash(into hasher: inout Hasher) {
    hasher.combine(firstName)
    hasher.combine(lastName)
    hasher.combine(age)
  }
}

In this example, you implemented the hash(into:) function, which calculates the hash value of a Person object based on its first name, last name, and age properties.

With this implementation, Person objects can be used as keys in a dictionary or elements in a set, because they conform to the Hashable protocol.

let person1 = Person(firstName: "John", lastName: "Doe", age: 30)
let person2 = Person(firstName: "Jane", lastName: "Doe", age: 25)

var personDict: [Person: String] = [:]

personDict[person1] = "Teacher"
personDict[person2] = "Doctor"

print(personDict[person1]) // Output: Optional("Teacher")
print(personDict[person2]) // Output: Optional("Doctor")