RandomPassword in Swift 3

Cocoa Programming for OS X (5th Edition) 1. Let's Get Started
1

GeneratePassword.swift

import Foundation

private let characters = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

func generateRandomString(_ length: Int) -> String {
  // Start with an empty string
  var string = ""
  
  // Append 'length' number of random characters
  for _ in 0..<length {
    string.append(generateRandomCharacter())
  }
  print("Random String: string= \(string)")
  return string
}

func generateRandomCharacter() -> Character {
  // Create a random index into the characters array
  let index: Int = Int(arc4random_uniform(UInt32(characters.characters.count)))

  var stringIndex: String.CharacterView.Index = characters.characters.startIndex
  stringIndex = characters.index(stringIndex, offsetBy: index)
  
  // Get and return a random character
  let character = characters[stringIndex]
  print("Random Character: index= \(index)\tcharacter= \(character)")
  return character
}