A simple LinkedList in Swift 3 using Sequence and IteratorProtocol

LinkedList.swift

//: Playground - noun: a place where people can play

import Foundation

class Node {
    let value: Any

    var next: Node?

    init(value: Any, next: Node?) {
        self.value = value
        self.next = next
    }
}

class LinkedList: Sequence {

    var head: Node?

    // MARK: <Sequence>

    func makeIterator() -> LinkedListIterator {
        return LinkedListIterator(self)
    }
}

struct LinkedListIterator: IteratorProtocol {
    let linkedList: LinkedList
    var current: Node?

    init(_ linkedList: LinkedList) {
        self.linkedList = linkedList
        self.current = linkedList.head
    }

    mutating func next() -> Node? {
        guard let thisCurrent = current else { return nil }
        current = thisCurrent.next
        return thisCurrent
    }
}

let node3 = Node(value: 3, next: nil)
let node2 = Node(value: 2, next: node3)
let node1 = Node(value: 1, next: node2)

let linkedList = LinkedList()
linkedList.head = node1

for node in linkedList {
    if let nodeInt = node.value as? Int {
        print("\(nodeInt)")
    }
}