Design Pattern: Builder

Builder.swift

class PersonBuilder {

  private final var name: String
  private final var age: String?
  private final var gender: String?

  init(name: String) {
    self.name = name
  }

  func with(age age: String) -> Self {
    self.age = age
    return self
  }

  func with(gender gender: String) -> Self {
    self.gender = gender
    return self
  }

  func build() -> Person {
    return Person(builder: self)
  }
}

struct Person {
  let name: String
  let age: String?
  let gender: String?

  init(builder: PersonBuilder) {
    name = builder.name
    age = builder.age
    gender = builder.gender
  }
}

let cegela = PersonBuilder(name: "Cegela").with(age: "20").with(gender: "M").build()
let mucuge = PersonBuilder(name: "Mucuge").with(gender: "M").with(age: "25").build()

Look this example of Builder using closure: https://github.com/elo7/Nayau/blob/master/nayau/Message.swift