Fizz Buzz in Swift 3 using extensions, switch, and tuples.

fizzbuzz-extension.swift

extension Int {
  func isDivisible(by number: Int) -> Bool {
    return (self % number == 0) 
  }
}

func fizzBuzz(_ number: Int) -> String {
  switch (number.isDivisibleBy(3), number.isDivisibleBy(5)) {
  case (true,  false): return "Fizz"
  case (false, true):  return "Buzz"
  case (true,  true):  return "Fizz Buzz"
  case (false, false): return String(number)
  }
}