How does one generate a random number in Apple's Swift language?

Question

I realize the Swift book provided an implementation of a random number generator. Is the best practice to copy and paste this implementation in one\'s own program? Or is t

Answer 1

The following code will produce a secure random number between 0 and 255:

extension UInt8 {
  public static var random: UInt8 {
    var number: UInt8 = 0
    _ = SecRandomCopyBytes(kSecRandomDefault, 1, &number)
    return number
  }
}

You call it like this:

print(UInt8.random)

For bigger numbers it becomes more complicated.
This is the best I could come up with:

extension UInt16 {
  public static var random: UInt16 {
    let count = Int(UInt8.random % 2) + 1
    var numbers = [UInt8](repeating: 0, count: 2)
    _ = SecRandomCopyBytes(kSecRandomDefault, count, &numbers)
    return numbers.reversed().reduce(0) { $0 << 8 + UInt16($1) }
  }
}

extension UInt32 {
  public static var random: UInt32 {
    let count = Int(UInt8.random % 4) + 1
    var numbers = [UInt8](repeating: 0, count: 4)
    _ = SecRandomCopyBytes(kSecRandomDefault, count, &numbers)
    return numbers.reversed().reduce(0) { $0 << 8 + UInt32($1) }
  }
}

These methods use an extra random number to determine how many UInt8s are going to be used to create the random number. The last line converts the [UInt8] to UInt16 or UInt32.

I don't know if the last two still count as truly random, but you can tweak it to your likings :)