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

1) Always the same number

You have to set a seed once to get "random" numbers from random():

randomSeed(Int(Date().timeIntervalSince1970)

Man page:

If no seed value is provided, the random() function is automatically seeded with a value of 1.

As the seed is always the same (1), you always get the same sequence of "random" numbers.

2) Alphanumeric string

To create your string without using NSString:

func randomString(length: Int) -> String {

    let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    let len = UInt32(letters.characters.count)

    var randomString = ""

    for _ in 0 ..< length {
        let rand = myCustomRandom(len)
        let randIndex = letters.index(letters.startIndex, offsetBy: Int(rand))
        let nextChar = letters[randIndex]
        randomString += String(nextChar)
    }

    return randomString
}