Find length of circular linked list in swift

Swift program for Find length of circular linked list . Here problem description and explanation.

import Foundation
// Swift 4 program for
// Count number of nodes in circular linked list 

// Define class of linked list Node
class LinkNode
{
	var data: Int;
	var next: LinkNode? ;
	init(_ data: Int, _ first: LinkNode? )
	{
		self.data = data;
		self.next = first;
	}
}
class CircularLinkedList
{
	var head: LinkNode? ;
	// Class constructor
	init()
	{
		self.head = nil;
	}
	// Insert node at end of circular linked list
	func insert(_ value: Int)
	{
		// Create a new node
		let node: LinkNode? = LinkNode(value, self.head);
		if (self.head == nil)
		{
			// First node of linked list
			self.head = node;
			node!.next = self.head;
		}
		else
		{
			var temp: LinkNode? = self.head;
			// Find the last node
			while (!(temp!.next === self.head))
			{
				// Visit to next node
				temp = temp!.next;
			}
			// Add new node at the last 
			temp!.next = node;
		}
	}
	func countNode() -> Int
	{
		if (self.head == nil)
		{
			return 0;
		}
		// Start with second node
		var temp: LinkNode? = self.head!.next;
		// This is used to count linked node
		var count: Int = 1;
		// iterate circular linked list
		while (!(temp === self.head))
		{
			count += 1;
			// Visit to next node
			temp = temp!.next;
		}
		return count;
	}
	static func main(_ args: [String])
	{
		let cll: CircularLinkedList? = CircularLinkedList();
		// Add nodes
		cll!.insert(1);
		cll!.insert(3);
		cll!.insert(5);
		cll!.insert(7);
		cll!.insert(9);
		cll!.insert(11);
		// Display result
		print(cll!.countNode());
	}
}
CircularLinkedList.main([String]());

Output

6