TableView-Tutorial-Alphabetical Index

User.swift

//
//  User.swift
//  TableViewDemo
//
//  Created by Bilguun Batbold on 22/2/19.
//  Copyright © 2019 ISEM. All rights reserved.
//

import Foundation

public struct User {
    let name: String
    let gender: String
    let email: String
}

public class UserManager {
    
    //set array of users (in reality this is usually from a network call
    public var users: [User] = [User(name: "Albert", gender: "Male", email: "albert@gmail.com"), User(name: "Bob", gender: "Male", email: "bob@gmail.com"), User(name: "Celine", gender: "Female", email: "celine@gmail.com"), User(name: "Derrick", gender: "Male", email: "derrick@gmail.com"), User(name: "Aldwin", gender: "Male", email: "aldwin@gmail.com")]
    
    private var userSection = [String]()
    private var userDictionary = [String:[User]]()
    
    //invoke sort user function when initialized
    init() {
        sortUser()
    }
    
    //this functions goes through each user and sets the first letter as a key. It then populates the list of users with the same key
    // this way we will end up with dictionary of users under their respecive alphabetical order
    private func sortUser() {
        for user in users {
            let key = "\(user.name[user.name.startIndex])".uppercased()
            if var userValue = self.userDictionary[key] {
                userValue.append(user)
            } else {
                self.userDictionary[key] = [user]
            }
            self.userSection = [String](self.userDictionary.keys).sorted()
        }
    }
    
    public var userSections: [String] {
        return userSection
    }
    
    public var userDictionaries: [String:[User]] {
        return userDictionary
    }
    
    //return total count
    public var userCount: Int {
        return users.count
    }
    
    public func addUser(user: User) {
        users.append(user)
    }
    
    //get user
    public func getUser(at index:Int) -> User {
        return users[index]
    }
    
    public func deleteUser(at index: Int) {
        users.remove(at: index)
    }
}

UserDataSourceProvider.swift

//
//  UserDataSourceProvider.swift
//  TableViewDemo
//
//  Created by Bilguun Batbold on 22/2/19.
//  Copyright © 2019 ISEM. All rights reserved.
//

import Foundation
import UIKit

public class UserDataSourceProvider: NSObject, UITableViewDelegate, UITableViewDataSource {

    
    //private var to hold the user manager
    private let userManager: UserManager
    
    //initialize the user manager
    init(userManager: UserManager) {
        self.userManager = userManager
    }

    //tableview delegates declared here
    
    
    //set the height of header
    public func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 30
    }
    
    //set the number of sections
    public func numberOfSections(in tableView: UITableView) -> Int {
        return userManager.userSections.count
    }
    //set the section index titles
    public func sectionIndexTitles(for tableView: UITableView) -> [String]? {
        return userManager.userSections
    }
    //set the section header titles
    public func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        return userManager.userSections[section].uppercased()
    }
    //set the header view
    public func tableView(_ tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int) {
        view.tintColor = #colorLiteral(red: 0.3333333333, green: 0.6392156863, blue: 0.9333333333, alpha: 1)
        let header = view as! UITableViewHeaderFooterView
        header.textLabel?.font = UIFont.systemFont(ofSize: 20, weight: .light)
        header.textLabel?.textColor = UIColor.white
    }
    //sets the nubmer of rows per section
    public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        let userKey = userManager.userSections[section]
        if let users = userManager.userDictionaries[userKey] {
            return users.count
        }
        return 0
    }

    //populate the user from the dictionary instead of the array now
    public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! UserTableViewCell
        let userKey = userManager.userSections[indexPath.section]
        if let users = userManager.userDictionaries[userKey.uppercased()] {
            cell.configure(user: users[indexPath.row])
        }
        
        return cell
    }
    
    public func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
        let delete = UITableViewRowAction(style: .destructive, title: "Delete") { (action, indexPath) in
            self.userManager.deleteUser(at: indexPath.row)
            tableView.deleteRows(at: [indexPath], with: .fade)
        }
        
        return [delete]
    }
    
}

Does this update the section titles if a row is deleted?