tableview expandable header

tableviewWithHeader.swift

    var selectedIndx = -1
    
    var newIndexSet = IndexSet()

    var thereIsCellTapped = false

func numberOfSections(in tableView: UITableView) -> Int {
        return 3
    }
    
    func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 30
    }
    
    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let button = UIButton(type: .system)
        button.setTitleColor(.darkGray, for: .normal)
        button.backgroundColor = #colorLiteral(red: 0.6666666865, green: 0.6666666865, blue: 0.6666666865, alpha: 1)
        button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 20)
        button.layer.cornerRadius = 5
        button.contentHorizontalAlignment = .left
        button.titleEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 0)
        button.addTarget(self, action: #selector(btnSectionClick(sender:)), for: .touchUpInside)
        
        if section == 0 {
            //adiciona titulo aqui
            button.setTitle("header 1", for: .normal)
        } else if section == 1 {
            button.setTitle("header 2", for: .normal)
        } else if section == 2 {
            button.setTitle("header 3", for: .normal)
        }
        
        button.tag = section
        
        return button
    }
    
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        if indexPath.section == selectedIndx && thereIsCellTapped{
            self.tableView.separatorStyle = .singleLine
            return 182
            
        }else{
            self.tableView.separatorStyle = .none
            return 4
        }
    }

//action when select header
@objc func btnSectionClick(sender:UIButton!){
        print("selected index",sender.tag)
        if selectedIndx != sender.tag {
            self.thereIsCellTapped = true
            self.selectedIndx = sender.tag
            newIndexSet = [selectedIndx]
            if sender.tag == 2 {
                tableView.separatorStyle = .singleLine
            }
            tableView.reloadSections(newIndexSet, with: .fade)
        } else {
            // there is no cell selected anymore
            if sender.tag == 2 {
                tableView.separatorStyle = .none
            }
            self.thereIsCellTapped = false
            self.selectedIndx = -1
            tableView.reloadSections(newIndexSet, with: .fade)
        }
    }