Table View is not reflecting change in size - swift

Question

//
// ViewController.swift
// practise
//
// Created by ali on 29/11/2019.
// Copyright © 2019 smartsolution. All rights reserved.
//
import UIKit
class nestedviewcontroller: UIViewController {
var maindatacells:[String]=["m1","m2","m3","m9"]
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}
extension nestedviewcontroller:UITableViewDataSource,UITableViewDelegate{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
tableView.rowHeight = UITableView.automaticDimension
return maindatacells.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! maintablecell
cell.lbltitle.text = maindatacells[indexPath.row]
cell.setdata(cont: self)
return cell
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
var height = cell.frame.height
}
func tableView(_ tableView: UITableView, didEndDisplaying cell: UITableViewCell, forRowAt indexPath: IndexPath) {
var heightjjj = cell.frame.height
}
}
class maintablecell:UITableViewCell,UITableViewDelegate,UITableViewDataSource{
#IBOutlet weak var tblheightconstraint:NSLayoutConstraint!
#IBOutlet weak var lbltitle:UILabel!
#IBOutlet weak var tblinside:UITableView!
var cellheight:CGFloat = 20
var parentcont:UIViewController!
override func awakeFromNib() {
super.awakeFromNib()
tblinside.delegate = self
tblinside.dataSource = self
}
func setdata(cont:UIViewController){
self.parentcont = cont
}
var datacells = ["i1","i2","i3","67"]
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return datacells.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: .default, reuseIdentifier: "cell")
cell.textLabel?.text = datacells[indexPath.row]
return cell
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
if indexPath.row == 0{
cellheight = 0
}
cellheight += cell.contentView.frame.height
if indexPath.row == datacells.count - 1{
// var tbl = self.superview as! UITableView
// tblinside.estimatedRowHeight = cellheight
// tbl.estimatedRowHeight = cellheight
tblheightconstraint.constant = cellheight
tblinside.beginUpdates()
tblinside.endUpdates()
self.setNeedsDisplay()
self.setNeedsLayout()
self.setNeedsUpdateConstraints()
self.parentcont.view.setNeedsLayout()
self.parentcont.view.setNeedsDisplay()
// var siz = self.frame.size
// //
// self.frame.size = CGSize(width: siz.width, height: siz.height + 30)
}
}
}
I am updating tableview size programmaticaly by changing its constraint. But tableview is not reflecting the change untill i refresh tableview by scrolling.I have tried many functions to update layout of main cell or tableview but i didnt find anything helping.
The tableview resize perfectly when i scroll the maintableview and the cell freshes