Append and Traverse a Doubly Linked List using Swift - iOS

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Let's Code :

 OK, let's see the result first , Adding some random city names to linked list and printing the linked list :




Let's create the node now :

 Node.swift
import Foundation

class Node: NSObject {
    var next: Node?
    weak var previous: Node?
    var value : String?
    init(value : String) {
        self.value = value
    }

}

Now implement linked list in another swift file

DoublyLinkedList. swift 


import UIKit

class DoublyLinkedList: NSObject {
    fileprivate var head : Node?
    private var tail : Node?
    override init() {
        super.init()
    }
    public var isEmpty : Bool {
        return head == nil
    }
    public var first : Node? {
        return head
    }
    public var last : Node? {
        return tail
    }
    func append(str : String) {
        let newNode = Node(value: str)
        if let tailNode = tail {
            tailNode.next = newNode
            newNode.previous = tailNode
        }
        else{
            head = newNode
        }
        tail = newNode
        print("Added new Node to Linked List : [ \(str) ]")
    }
    func printDoublyLiskedList() {
        var node = self.first
        print("\nPrinting Doubly Linked List : ")
        while node != nil {
            let nodeValue : String = node!.value!
            print("\(nodeValue)")
            node = node?.next
        }
    }
}

Use the linked list where you want - just showing an example below

ViewController.swift

import UIKit


class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let doublyLL = DoublyLinkedList()
        doublyLL.append(str: "Kolkata")
        doublyLL.append(str: "Hyderabad")
        doublyLL.append(str: "Pune")
        doublyLL.printDoublyLiskedList()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}


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