Random Alphanumeric String Linux Swift 3

Question

Im having 2 problems when trying to generate a random string in Linux with Swift 3.

1. arc4random_uniform is not available in Linux only on BSD. SO i was able

Answer 1

Swift 4.2, Ubuntu 16.04

let letters : String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let len = letters.count
var randomString:String = ""
for _ in 0 ..< length {
   let rand = Int.random(in: 0..