Hasher, how it works

Hash-Part2.swift

// Using hasher. Actually, you will never use it directly.
var hasher = Hasher()
hasher.combine("Hello")
hasher.combine("World")
hasher.combine(2020)
let hashValue = hasher.finalize()

// This is the correct way to implement Hashable.
extension YourStruct: Hashable {
  func hash(into hasher: inout Hasher) {
    hasher.combine("Hello")
    hasher.combine("World")
    hasher.combine(2020)
  }
}