Problem to implement scanner NFC in swift (IOS)

Question

I have this class to implement the scanner with NFC in my app. I have seen different tutorials and many people use this class. The error that it returns:

Type 'DniNFCViewController' does not conform to protocol 'NFCNDEFReaderSessionDelegate'

This error suggest me to add new methods (in my case readerSession) but they are already implemented. However, I have implemented this class in a new project and it works correctly.

//
//  DniNFCViewController.swift
//  SSLSignature
//
//  Created by Ismael Márquez on 20/2/24.
//  Copyright © 2024 aralink. All rights reserved.
//

import UIKit
import CoreNFC

class DniNFCViewController: UIViewController, NFCNDEFReaderSessionDelegate {
    
    var nfcSession: NFCNDEFReaderSession?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }
    
    @IBAction func startNFCSession(_ sender: Any) {
        nfcSession = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)
        nfcSession?.begin()
    }
    
    // MARK: - NFCNDEFReaderSessionDelegate
    
    func readerSession(_ session: NFCNDEFReaderSession, didInvalidateWithError error: Error) {
        print("Session invalidated with error: \(error.localizedDescription)")
    }
    
    func readerSession(_ session: NFCNDEFReaderSession, didDetectNDEFs messages: [NFCNDEFMessage]) {
        // Handle NFC tag detection here
        for message in messages {
            for record in message.records {
                // Process NDEF records
                // This is where you would handle the data read from the NFC tag
                print("Record payload: \(record.payload)")
            }
        }
    }
}

how to resolve the problem and why this error happens?