Move a specific occurrence to end of linked list in swift

Swift program for Move a specific occurrence to end of linked list. Here problem description and explanation.

import Foundation
// Swift 4 program for
// Move given occurrence to the end of linked list

// Linked list node
class LinkNode
{
	var data: Int;
	var next: LinkNode? ;
	init(_ data: Int)
	{
		self.data = data;
		self.next = nil;
	}
}
class SingleLL
{
	var head: LinkNode? ;
	init()
	{
		self.head = nil;
	}
	// Add new node at the end of linked list
	func insert(_ value: Int)
	{
		// Create a node
		let node: LinkNode? = LinkNode(value);
		if (self.head == nil)
		{
			self.head = node;
		}
		else
		{
			var temp: LinkNode? = self.head;
			// Find last node
			while (temp!.next  != nil)
			{
				// Visit to next node
				temp = temp!.next;
			}
			// Add node at last position
			temp!.next = node;
		}
	}
	// Display all Linked List elements
	func display()
	{
		if (self.head  != nil)
		{
			var temp: LinkNode? = self.head;
			while (temp  != nil)
			{
				// Display node value
				print(" ",temp!.data, terminator: " ");
				// Visit to next node
				temp = temp!.next;
			}
		}
		else
		{
			print("Empty Linked list");
		}
	}
	// Move all occurrence of given element into the 
	// end of linked list position
	func moveNodes(_ element: Int)
	{
		if (self.head == nil)
		{
			print("Empty linked list");
		}
		else
		{
			// Some useful auxiliary variables
			var temp: LinkNode? = self.head;
			var prev: LinkNode? = nil;
			var nodes: LinkNode? = nil;
			var current: LinkNode? = nil;
			// Move a particular occurrence to end of linked list
			while (temp  != nil)
			{
				current = temp;
				// Visit to next node
				temp = temp!.next;
				if (current!.data == element)
				{
					// Find move element
					if (self.head === current)
					{
						// Move the front node element 
						// to the end position
						self.head = temp;
					}
					if (prev  != nil)
					{
						// When have a intermediate node
						// Unlink the move node
						prev!.next = temp;
					}
					current!.next = nodes;
					nodes = current;
				}
				else
				{
					prev = current;
				}
			}
			if (self.head == nil && nodes  != nil)
			{
				// All same nodes are exist in linked list
				self.head = nodes;
			}
			else if (prev  != nil && nodes  != nil)
			{
				// Add occurrence to end
				prev!.next = nodes;
			}
			else
			{
				// When given occurrences element are not found
				print("Occurrences element are not found : "
					+ String(element));
			}
		}
	}
	static func main(_ args: [String])
	{
		let sll: SingleLL = SingleLL();
		// Linked list
		// 1 → 2 → 3 → 4 → 4 → 5 → 6 → 7 → NULL
		sll.insert(7);
		sll.insert(1);
		sll.insert(2);
		sll.insert(7);
		sll.insert(3);
		sll.insert(2);
		sll.insert(7);
		let occurrence: Int = 7;
		print("Before move occurrence "
			+ String(occurrence) + " to end");
		//display all node
		sll.display();
		print("\nAfter move occurrence "
			+ String(occurrence) + " to end");
		sll.moveNodes(occurrence);
		sll.display();
	}
}
SingleLL.main([String]());

Output

Before move occurrence 7 to end
  7   1   2   7   3   2   7
After move occurrence 7 to end
  1   2   3   2   7   7   7