Развернуть и свернуть ячейки таблицы

Я могу расширять и сворачивать ячейки, но я хочу вызвать функции (развернуть и свернуть) внутри UITableViewCell, чтобы изменить название кнопки.

import UIKit

class MyTicketsTableViewController: UITableViewController {

    var selectedIndexPath: NSIndexPath?
    var extraHeight: CGFloat = 100

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 5
    }

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! MyTicketsTableViewCell
        return cell
    }

    override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
        if(selectedIndexPath != nil && indexPath.compare(selectedIndexPath!) == NSComparisonResult.OrderedSame) {
            return 230 + extraHeight
        }

        return 230.0
    }

    override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        if(selectedIndexPath == indexPath) {
            selectedIndexPath = nil
        } else {
            selectedIndexPath = indexPath
        }

        tableView.beginUpdates()
        tableView.endUpdates()
    }
}

import UIKit

class MyTicketsTableViewCell: UITableViewCell {

    @IBOutlet weak var expandButton: ExpandButton!
    @IBOutlet weak var detailsHeightConstraint: NSLayoutConstraint!

    var defaultHeight: CGFloat!

    override func awakeFromNib() {
        super.awakeFromNib()

        defaultHeight = detailsHeightConstraint.constant

        expandButton.button.setTitle("TAP FOR DETAILS", forState: .Normal)
        detailsHeightConstraint.constant = 30
    }

    func expand() {
        UIView.animateWithDuration(0.3, delay: 0.0, options: .CurveLinear, animations: {
            self.expandButton.arrowImage.transform = CGAffineTransformMakeRotation(CGFloat(M_PI * 0.99))
            self.detailsHeightConstraint.constant = self.defaultHeight
            self.layoutIfNeeded()

            }, completion: { finished in
                self.expandButton.button.setTitle("CLOSE", forState: .Normal)
        })
    }

    func collapse() {
        UIView.animateWithDuration(0.3, delay: 0.0, options: .CurveLinear, animations: {
            self.expandButton.arrowImage.transform = CGAffineTransformMakeRotation(CGFloat(M_PI * 0.0))
            self.detailsHeightConstraint.constant = CGFloat(30.0)
            self.layoutIfNeeded()

            }, completion: { finished in
                self.expandButton.button.setTitle("TAP FOR DETAILS", forState: .Normal)
        })
    }

}