Superbowl Squares random number generator

superbowl_squares.swift

import Foundation

/// http://stackoverflow.com/a/24029847/4992155
extension MutableCollection where Indices.Iterator.Element == Index {
    /// Shuffles the contents of this collection.
    mutating func shuffle() {
        let c = count
        guard c > 1 else { return }
        
        for (unshuffledCount, firstUnshuffled) in zip(stride(from: c, to: 1, by: -1), indices) {
            let d: IndexDistance = numericCast(arc4random_uniform(numericCast(unshuffledCount)))
            guard d != 0 else { continue }
            let i = index(firstUnshuffled, offsetBy: d)
            swap(&self[firstUnshuffled], &self[i])
        }
    }
}

extension Sequence {
    /// Returns an array with the contents of this sequence, shuffled.
    func shuffled() -> [Iterator.Element] {
        var result = Array(self)
        result.shuffle()
        return result
    }
}

func axis(forTeam team: String) -> (String, [Int]) {
    return (team, (0...9).shuffled())
}


print(["Eagles", "Patriots"].map{ axis(forTeam: $0) })

I wrote the anonymous source gist, but didn't realize I wasn't logged in.