KeylessUserDefaultsPersonExtension.swift

extension Person: DefaultConvertible {
  private static let firstNameKey = "first_name"
  private static let lastNameKey = "last_name"
  private static let ageKey = "age"
  
  var serialized: [String : AnyObject] {
    return
      [
        Person.firstNameKey: firstName as AnyObject,
        Person.lastNameKey: lastName as AnyObject,
        Person.ageKey: age as AnyObject
      ]
  }
  
  init?(dictionary: [String : AnyObject])
  {
    guard let firstName = dictionary[Person.firstNameKey] as? String,
          let lastName = dictionary[Person.lastNameKey] as? String,
          let age = dictionary[Person.ageKey] as? Int
      else { return nil }
    
    self.firstName = firstName
    self.lastName = lastName
    self.age = age
  }
}