How to register a cell for UITableViewCell reuse

Register TableView Cell or nib

let cellIdentifier = "CellIdentifier"
override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellIdentifier)
    }

OR 

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "DefaultCell")!
    return cell
}


The other option is to use register() with an Interface Builder nib file, like this:

tableView.register(UINib(nibName: "yourNib", bundle: nil), forCellReuseIdentifier: "CellFromNib")

// Register table cell class from nib
    let cellNib = UINib(nibName: "TableCellNib", bundle: bundle)
    self.tableView.registerNib(cellNib, forCellReuseIdentifier: self.tableCellId)

// Register table cell class from nib
let cellNib = UINib(nibName: "TableCellNib", bundle: bundle)
self.tableView.registerNib(cellNib, forCellReuseIdentifier: self.tableCellId)