小编Chr*_*ris的帖子

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
   self.selectedClubState = stateNamesForDisplay[indexPath.row]
   self.performSegueWithIdentifier ("Cities", sender: self)
}

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    var clubsToPassToCitiesViewController = [clubObject]()
    if segue.identifier == "Cities" {
        for club in clubsForTable{
            if club.clubState == self.selectedClubState{
                clubsToPassToCitiesViewController.append(club)
            }
        }
       let citiesView = segue.destinationViewController as? citiesViewController
       citiesView?.clubsForChosenCity = clubsToPassToCitiesViewController
   }
}

Segue正在执行两次,导致下一个VC.我怎样才能防止这种情况发生？

class HomeViewController: UIViewController {

    @IBOutlet weak var userNameLabel: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Show the current visitor's username
        if let pUserName = PFUser.currentUser()?["username"] as? String {
            self.userNameLabel?.text = "@" + pUserName
        }
    }

    override func viewWillAppear(animated: Bool) {
        if (PFUser.currentUser() == nil) {
            dispatch_async(dispatch_get_main_queue(), { () -> Void in

                let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("Login")
                self.presentViewController(viewController, animated: true, completion: nil)
            })
        }

    }
    @IBAction func commentAction(sender: AnyObject) {

        self.performSegueWithIdentifier("CommentSegue", sender: self)
    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: …