KeylessUserDefaultsIdealUsage2.swift

let defaults = Defaults()
let hasLoggedIn = true
defaults.save(true, forKey: .LoggedIn)
defaults.save(false, forKey: .NotificationsEnabled)

let regularOrder = Order(item: "Cold Brew", size: .Large)
let alternateOrder = Order(item: "Latte", size: .Small)
defaults.save(regularOrder)
defaults.save(alternateOrder, forKey: .Alternate)

class Defaults {
  func save<T: DefaultConvertible>(toSave: T, forKey key: T.Key = .Default) { ... }
  func fetch<T: DefaultConvertible>(type: T.Type, forKey key: T.Key = .Default) -> T? { ... }
}