c.swift

enum Foo {
  case A(String, Int)
  case B(Int, String, String)
  case C(Int)
}

func thingy(arg: Foo) -> String {
  var r: String
  switch(arg) {
  case .A(let s, let i), .B(let i, _, let s):
    r = "\(s)\(i)"
  case .C:
    r = "c"
  }
  return r
}