inserted rows table view not showing properly

//
//  ViewController.swift
//  PagginationSwift3
//
//  Created by Nazmul Hasan on 8/2/17.
//  Copyright © 2017 Nazmul hasan. All rights reserved.
//



import UIKit

class Student{
    var name : String = ""
}

class NewsViewController: UIViewController {
    
    let newsfeedCellId = "newsfeedCellId"
    
    var tableViewIndex : IndexPath?
    var students : [[Student]]?
    
    var count = 0
    var firstIndex = 0
    
    var itemNumber = 0

    var uploadedSection : Int?
    // variable to save the last position visited, default to zero
    fileprivate var lastContentOffset: CGFloat = 0

    override func viewDidLoad() {
        self.registerViews()
        self.setupViews()
       students = [[Student]]()
       
        initUpdateUI()
    }
    
    
    lazy  var newsFeedTableView : UITableView = {
        var tableView = UITableView()
        tableView.backgroundColor = UIColor.white
        tableView.dataSource = self
        tableView.separatorStyle = .none
        tableView.delegate = self
        tableView.translatesAutoresizingMaskIntoConstraints = false
        return tableView
    }()
}

extension NewsViewController  {
    
     func setupViews() {
        self.view.addSubview(newsFeedTableView)
        self.newsFeedTableView.fillSuperview()//rander the full screen
    }
    
     func registerViews() {
        newsFeedTableView.register(NewsTableViewViewCell.self, forCellReuseIdentifier: newsfeedCellId)
    }
}


extension NewsViewController : UITableViewDataSource{
    func numberOfSections(in tableView: UITableView) -> Int {
        return students?.count ?? 0
    }
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return students?[section].count ?? 0
    }
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        
        return 400
    }

    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        
        guard let indexpath = tableViewIndex else { return }

        if self.lastContentOffset > scrollView.contentOffset.y {
          //scrolling up
          //adding top of the array
            //TODO FIX
        } else if self.lastContentOffset < scrollView.contentOffset.y  {
            //scrolling down
           //adding  bottom of the array
            if let _students   =   students?[indexpath.section]{
                if _students.count / 2 == indexpath.row + 1  {
                    if uploadedSection != indexpath.section {
                        uploadedSection = indexpath.section
                        self.oldestState()
                    }
                }
            }

            
        }
        self.lastContentOffset = scrollView.contentOffset.y
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: newsfeedCellId, for: indexPath) as! NewsTableViewViewCell
        tableViewIndex = indexPath
        if let  _states = students?[indexPath.section]{
            cell.student = _states[indexPath.row]
            cell.backgroundColor = UIColor.blue
        }
        return cell
    }
    
}

extension NewsViewController : UITableViewDelegate {
    
}

//MARK:- Load Data to the UI
extension NewsViewController  {
    
    func initUpdateUI(){
        self.students?.append(getdata())
        self.newsFeedTableView.reloadData()
    }
    //scrolling up time calling this method
    func newestState(){
      //todo ..
    }
    //scrolling down time calling this method
    func oldestState(){
        self.newsFeedTableView.beginUpdates()
        self.students?.append(getdata()) //Update state  property
        
        let indexPaths = (0..<(getdata().count)).map { IndexPath(row: $0, section: (self.students?.count)! - 1) }
        print(indexPaths)
        self.newsFeedTableView.insertSections([(self.students?.count)! - 1], with: UITableViewRowAnimation.automatic)
        self.newsFeedTableView.insertRows(at: indexPaths, with: UITableViewRowAnimation.automatic)
        self.newsFeedTableView.endUpdates()
        
    }
    
    
    func getdata() -> [Student]{
        
        var _students = [Student]()
        for i in  itemNumber..<(itemNumber + 4) {
            let student = Student()
            student.name = "\(i)"
             print("adding student roll number : \(student.name)")
            _students.append(student)
        }
        itemNumber  +=  4
        return _students
    }
}

class NewsTableViewViewCell : BaseTableViewCell{
    
    var student : Student?{
        didSet{
            statesTextView.text = student?.name
        }
    }
    
    lazy var  statesTextView: UITextView = {
        let textView = UITextView()
        textView.translatesAutoresizingMaskIntoConstraints = false
        return textView
    }()
    
    override func setupViews() {
        super.setupViews()
        addSubview(statesTextView)
        statesTextView.anchor(self.topAnchor, left:  self.leftAnchor, bottom: self.bottomAnchor, right: self.rightAnchor, topConstant: 5, leftConstant: 10, bottomConstant: 2, rightConstant: 5, widthConstant: 0, heightConstant: 0)
    }
}

class BaseTableViewCell: UITableViewCell {
    
    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        setupViews()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setupViews()  {
        print("calling cell baseTableCell")
    }
}