Switching on optional enums

optionalEnum.swift

enum Coin {
  case heads
  case tails
}
var result: Coin?

// You can pattern match against it like an optional:
switch result {
case .heads?: print("heads")
case .tails?: print("tails")
case nil: print("not yet flipped") // exhaustive
}

// Or, you can pattern match it agains the the optional enum that wraps all optional types:
switch result {
case .Some(.heads): print("heads")
case .Some(.tails): print("tails")
case .None: print("not yet flipped") // also exhaustive
}

// This even works on optional booleans
switch tab?.paid {
case true?:
  tabState = .paid
case false?:
  tabState = .open
case nil:
  tabState = .empty
}