Linked List in Swift: A Beginner's Guide

Hello everyone! In this article, we will discuss the Linked List data structure and write a program in Swift to understand how it works.

Singly Linked List

A Linked List is a container-like structure where each element is a Node. A node contains two things:

Value: The actual data.
Next: The address (reference) of the next Node.

The starting node is called the Head, and the last node (which refers to nil) is called the Tail.

Example: Head -> [1] -> [2] -> [3] -> Nil

1. Creating the Node Class

We use a generic class so our Linked List can store any data type.

class Node<T> {
    var value: T
    var next: Node?
    
    init(value: T) {
        self.value = value
        self.next = nil
    }
}

2. Creating the Linked List Class

The LinkedList class keeps track of the head.

class LinkedList<T> {
    var head: Node<T>?
    
    func isEmpty() -> Bool {
        return head == nil
    }
}

3. Inserting Nodes (Append)

To add a node, we traverse to the end of the list and link the new node to the last node's next property.

func append(_ value: T) {
    let newNode = Node(value: value)
    
    if head == nil {
        head = newNode
        return
    }
    
    var current = head
    while current?.next != nil {
        current = current?.next
    }
    current?.next = newNode
}

4. Displaying the List

We iterate through the list and print each value until we hit nil.

func display() {
    var current = head
    while current != nil {
        print(current!.value, terminator: " -> ")
        current = current?.next
    }
    print("nil")
}

Full Implementation & Usage

var list = LinkedList<String>()
list.append("Chandan")
list.append("Kumar")
list.append("Dash")

list.display()
// Output: Chandan -> Kumar -> Dash -> nil

Thank you for reading! If you found this helpful, stay tuned for more Swift content.