Open Closed Principle in Swift

open_closed_principle_anti.swift

enum Fruit {
  case apple
  case orange
  case banana
  case grape
}

func functionA(_ fruit: Fruit) {
  switch fruit {
    case .apple:
      // do something
    case .orange:
      // do something
    case .banana:
      // do something
    case .grape:
      // do something
  }
}

func functionB(_ fruit: Fruit) {
  switch fruit {
    case .apple:
      // do something
    default:
      // break or do default something
  }
}

func functionC(_ fruit: Fruit) {
  if case .apple = fruit {
    // do something
  } else {
    // do something
  }
}