gistfile1.txt

func foo(n: Int) -> Int {
  switch(n) {
  case 0:
    return 1
  default:
    return n
  }
}

Missing return in a function expected to return 'Int'

func foo(n: Int) -> Int {
  switch(n) {
  case 0:
    return 1
  }
  return n
}

Switch must be exhaustive, consider adding a default clause

func foo(n: Int) -> Int {
  switch(n) {
  case 0:
    return 1
  default:
    return n
  }
  return n
}

Bingo