正在跳过performSegueWithIdentifier * SWIFT

Question

I have a UITableViewController that I would like people to access as the main page. I do have a login view controller but I do not want this to be my initial view controller. I have an if statement checking if the user has logged in previously. If not, I would like to perform a segue to the login view controller. When I run the app however, it goes through the if statement, recognizes that the user is == nil, and then goes right over the performSegueWithIdentifier operation.

override func viewDidLoad() {
        super.viewDidLoad()

        if user == nil {

            self.performSegueWithIdentifier("LoginSegue", sender: self)

        }
}

Any idea why?

Answer 1

You should move your code into the viewWillAppear or viewDidAppear method. Then it should use properly.

But now the view flickers a short time. To remove that flickering, just hide the view in your viewWillApear method:

self.view.hidden = true

Also the viewDidLoad method doesn't get called everytime the view appears but only the first time it loads. If you for example perform a segue and return back to the view, it doesn't load again but only calls viewWillAppear and viewDidAppear again.

Answer 2

For Swift 3.0, try to run on the main thread like this.

DispatchQueue.main.async {
    self.performSegue(withIdentifier: "LoginSegue", sender: self)
}

Answer 3

Without more information it is hard to say.

1. Do you have a button or something with an already established segue, and have you provided the identifier for the segue? I made a similar call in viewDidLoad and it worked.

2. Have you embedded the view controller in a UINavigationController? If not, performing the segue is not possible. It sounds like you're using a UITableViewController, which inherits from UIViewController. So this may be the issue.

Answer 4

dispatch_async(dispatch_get_main_queue(), { () -> Void in   
        let viewController:UIViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ViewControllerClassId") as! ViewControllerClassName
        self.presentViewController(viewController, animated: true, completion: nil)
    })

this code solved my problem. use my code instead of self.performSegueWithIdentifier("LoginSegue", sender: self) and give your destination ViewController an ID like ViewControllerClassId