DetailVC.swift

import UIKit

protocol ChangedTitleDelegate {
    func titleChanged(title: String)
}

class DetailViewController: UIViewController {
    
    var delegate : ChangedTitleDelegate?
    
    var itemTitle = ""
    var itemDescription = "" 
    let attributes : [NSAttributedString.Key: Any] = [
        .font: UIFont.systemFont(ofSize: 23),
        .foregroundColor: UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.5),
    ]    
    var attributedTitle: NSAttributedString {
        return NSAttributedString(string: itemDescription.convertHtml().string, attributes: attributes)
    }
    
    @IBOutlet weak var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        delegate?.titleChanged(title: itemTitle)
        setupNavBar()
        tableView.rowHeight = UITableView.automaticDimension
    }
    
    func setupNavBar() {
        title = itemTitle
        navigationItem.largeTitleDisplayMode = .always
    }
    
}

// MARK: - Extensions
extension DetailViewController: UITableViewDelegate, UITableViewDataSource {
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 1
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
        
        cell.textLabel?.attributedText = attributedTitle
        cell.textLabel?.numberOfLines = 0
        
        return cell
    }
}

extension String {
    func convertHtml() -> NSAttributedString {
        guard let data = data(using: .utf8) else { return NSAttributedString() }
        do {
            return try NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil)
        } catch { return NSAttributedString() }
    }
}

Feed.swift

import UIKit
import CoreData

class NewsViewController: UIViewController {
    
    private var items = [Item]()
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    var isLoading = false
    
    @IBOutlet weak var segmentedControl: UISegmentedControl!
    @IBOutlet weak var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 120.0
        
        fetchData()
        tableView.reloadData()
    }
    
    // MARK: - Fetching data
    
    private func fetchData() {
        let parser = FeedParser()
        let queue = DispatchQueue.global(qos: .background)
        let newsURL = url(category: self.segmentedControl.selectedSegmentIndex)
        isLoading = true
        queue.async {
            parser.parseFeed(url: newsURL) { (rssItems) in
                
                for item in rssItems {
                    let newItem = Item(context: self.context)
                    newItem.title = item.title
                    newItem.fdescription = item.description
                    newItem.category = item.category
                    self.items.append(newItem)
                }
                self.saveItems()
                DispatchQueue.main.async {
                    self.isLoading = false
                    self.tableView.reloadData()
                }
            }
        }
    }
    
    @IBAction func switchTableViewAction(_ sender: UISegmentedControl) {
        fetchData()
        tableView.reloadData()
    }
    
    private func url(category: Int) -> String {
        let urlString: String
        switch category {
        case 0: urlString = "http://feeds.reuters.com/reuters/businessNews"
        case 1: urlString = "http://feeds.reuters.com/reuters/entertainment"
        default: urlString = ""
        }
        
        return urlString
    }
    
    // MARK: - Model manipulation methods
    
    func saveItems() {
        do { try context.save() }
        catch { print("Error saving items: \(error)") }
    }
    
    func loadItems() {
        let request : NSFetchRequest<Item> = Item.fetchRequest()
        do { items = try context.fetch(request) }
        catch { print("Error fetching data from context: \(error)") }
    }
    
}


// MARK: - Extensions
extension NewsViewController: UITableViewDataSource, UITableViewDelegate {
    
    func numberOfSections(in tableView: UITableView) -> Int {
        switch segmentedControl.selectedSegmentIndex {
        case 0: return 1
        case 1: return 2
        default: return 1
        }
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if isLoading {
            return 1
        } else {
            return items.count
        }
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        if isLoading {
            let cell = tableView.dequeueReusableCell(withIdentifier:
                "LoadingCell", for: indexPath)
            let spinner = cell.viewWithTag(100) as!
            UIActivityIndicatorView
            spinner.startAnimating()
            return cell
        } else {
            let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! NewsTableViewCell
            let item = items[indexPath.item]
            cell.item = item
            return cell
        }
    }
    
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let item = items[indexPath.row]
        let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DetailViewController") as! DetailViewController
        vc.itemTitle = item.title!
        vc.itemDescription = item.fdescription!
        navigationController?.pushViewController(vc, animated: true)
        tableView.deselectRow(at: indexPath, animated: true)
    }
}

Main.swift

class MainTableViewController: UITableViewController, ChangedTitleDelegate {
    
    var timer = Timer()
    var timeString = ""
    
    var titleLabel : String?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(timeNowString), userInfo: nil, repeats: true)
    }
    
    // MARK: - Table view data source
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 3
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
        
        switch indexPath.row {
        case 0:
            cell.textLabel?.text = "My Name"
            cell.detailTextLabel?.text = "Daria"
        case 1:
            cell.textLabel?.text = "Date and time"
            cell.detailTextLabel?.text = timeNowString() as String
        case 2:
            cell.textLabel?.text = titleLabel
            cell.detailTextLabel?.text = ""
        default:
            break
        }
        
        return cell
    }
    
    @objc func timeNowString() -> NSString {
        let date = NSDate()
        let formatter = DateFormatter()
        formatter.locale = NSLocale(localeIdentifier:"en_US") as Locale
        formatter.dateFormat = "MM/dd/yyyy, HH:mm:ss"
        let timeString = formatter.string(from: date as Date)
        return timeString as NSString
    }
    
    func titleChanged(title: String) {
        titleLabel = title
    }
    
}

Parser.swift

import Foundation
import UIKit
import CoreData

struct RSSItem {
    var title : String
    var link : String
    var description : String
    var category : String
    var pubDate : String
}

class FeedParser: NSObject, XMLParserDelegate
{
    private var rssItems: [RSSItem] = []
    private var currentElement = ""
    
    private var currentTitle: String = "" {
        didSet {
            currentTitle = currentTitle.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        }
    }
    private var currentLink: String = "" {
        didSet {
            currentLink = currentLink.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        }
    }
    private var currentDescription: String = "" {
        didSet {
            currentDescription = currentDescription.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        }
    }
    private var currentCategory: String = "" {
        didSet {
            currentCategory = currentCategory.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        }
    }
    private var currentPubDate: String = "" {
        didSet {
            currentPubDate = currentPubDate.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        }
    }
    private var parserCompletionHandler: (([RSSItem]) -> Void)?
    
    func parseFeed(url: String, completionHandler: (([RSSItem]) -> Void)?)
    {
        self.parserCompletionHandler = completionHandler
        
        let request = URLRequest(url: URL(string: url)!)
        let urlSession = URLSession.shared
        let task = urlSession.dataTask(with: request) { (data, response, error) in
            guard let data = data else {
                if let error = error {
                    print("Failure! \(error.localizedDescription)")
                } else {
                    print("Success! \(response!)")
                }
                return
            }
            let parser = XMLParser(data: data)
            parser.delegate = self
            parser.parse()
        }
        task.resume()
    }
    
    // MARK: - XML Parser Delegate
    
    func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:])
    {
        currentElement = elementName
        if currentElement == "item" {
            currentTitle = ""
            currentLink = ""
            currentDescription = ""
            currentCategory = ""
            currentPubDate = ""
        }
    }
    
    func parser(_ parser: XMLParser, foundCharacters string: String)
    {
        switch currentElement {
        case "title" : currentTitle += string
        case "link" : currentLink += string
        case "description" : currentDescription += string
        case "category" : currentCategory += string
        case "pubDate" : currentPubDate += string
        default: break
        }
    }
    
    func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?)
    {
        if elementName == "item" {
            let rssItem = RSSItem(title: currentTitle, link: currentLink, description: currentDescription, category: currentCategory, pubDate: currentPubDate)
            self.rssItems.append(rssItem)
        }
    }
    
    func parserDidEndDocument(_ parser: XMLParser) {
        parserCompletionHandler?(rssItems)
    }
    
    func parser(_ parser: XMLParser, parseErrorOccurred parseError: Error)
    {
        print("Failure! \(parseError.localizedDescription)")
    }
    
}