RandomQueue

RandomQueue.swift

class RandomQueue<T> : IteratorProtocol {
    typealias Element = T
    
    var position = 0
    var positions : [Int] = []
    let items : [T]
    
    init(items:[T]){
        self.items = items
    }
    
    func next() -> T? {
        guard positions.count != items.count else { return nil }
        return items[random()]
    }
    
    fileprivate func random() -> Int {
        var ranNumber : Int = 0
        repeat {
            ranNumber = Int(arc4random_uniform(UInt32(items.count)))
        } while (positions.contains(ranNumber))
        positions.append(ranNumber)
        return ranNumber
    }
}