make custom cell's text field active after reloadData (swift)

var addRow = 0
var subtasksArray = ["one", "two"]

class AddEditTaskController: UIViewController, UITableViewDataSource,
UITableViewDelegate, CustomCellDelegate {

    func reloadTable() {
        subtaskTable.reloadData()
    }

    @IBOutlet weak var subtaskTable: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()

        var tblView =  UIView(frame: CGRectZero)
        subtaskTable.tableFooterView = tblView
        subtaskTable.tableFooterView?.hidden = true
        subtaskTable.backgroundColor = UIColor.clearColor()
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return subtasksArray.count + addRow
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

        var cell: SubtaskCell = subtaskTable.dequeueReusableCellWithIdentifier("subtaskCell") as SubtaskCell

        cell.delegate = self 
        return cell 
    }

protocol CustomCellDelegate {
    func reloadTable()
}

class SubtaskCell: UITableViewCell, UITextFieldDelegate {

    var delegate: CustomCellDelegate?

    @IBOutlet weak var subtaskTextField: UITextField!

    override func awakeFromNib() {
        super.awakeFromNib()

        subtaskTextField.delegate = self
    }

    func textFieldDidBeginEditing(textField: UITextField) {
        addRow += 1
        delegate?.reloadTable() 

        subtaskTextField.becomeFirstResponder()
    }

    func textFieldDidEndEditing(textField: UITextField) {

    }

    override func setSelected(selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
    }
}