transfer the variable from one ViewController to another

[zymir]

Please indicate how the variable value can be transferred from one ViewController's to another? I am now following: Cell compression process

tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath):
                    let appDelegate = UIApplication.sharedApplication().delegate! as! AppDelegate
                    let TaskData: TaskListTableViewController = TaskListTableViewController()
                    TaskData.catID = currentCell.categoryID!.text  // В этом месте пытаюсь передать данные

                    let initialViewController = self.storyboard!.instantiateViewControllerWithIdentifier("taskListTable")// as! UIViewController
                    appDelegate.window?.rootViewController = initialViewController
                    appDelegate.window?.makeKeyAndVisible()

В контроллере TaskListTableViewController переменная объявлена:
class TaskListTableViewController: UITableViewController, UIPageViewControllerDelegate {
    var catID: String?

//------------------------------

...

...

But in the performance of the catID, the nil returns.

Can you tell me what the problem is?

[charlenef]

Better use segue:

1 PKM from the counteraller to which we move to the controller:

2 Identifier segue:

3 Redefined prepareForSegue As you wish.

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    let controller = segue.destinationViewController as! SecondVC //приводим `destinationViewController` к нужному нам `SecondVC`
    controller.s = "Woohoo" //s - строковая переменная, которой присваивем "Woohoo"
}

4 at the required event. performSegueWithIdentifier("SHOWVC", sender: self)