UIAlertController whose view is not in the window hierarchy

Question

I'm trying to create an app with Swift and Parse. I'm using Xcode 7 and Swift 2. I want to show a alert message when User is login failed, here is my function:

func logInViewController(logInController: PFLogInViewController, didFailToLogInWithError error: NSError?){
    let alertLoginFailed = UIAlertController(title: "Login Failed", message: "Your username or password is invalid!", preferredStyle: UIAlertControllerStyle.Alert)
    alertLoginFailed.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
    self.presentViewController(alertLoginFailed, animated: true, completion: nil)
    print("Login failed.........!")
}

But I've got this error when run in the emulator:

2015-10-02 11:32:39.988 RedString[2089:886501] Warning: Attempt to present <UIAlertController: 0x7a934400> on <MyProject.ViewController: 0x7b985150> whose view is not in the window hierarchy!
Login failed.........!

I've googled about it, but I didn't found the clear solution.

Here is my whole class:

import UIKit
import Parse
import ParseUI
class ViewController: UIViewController, PFLogInViewControllerDelegate, PFSignUpViewControllerDelegate {

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

    override func viewDidAppear(animated: Bool) {
        self.setupLoginView()
    }

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

    func logInViewController(logInController: PFLogInViewController, didLogInUser user: PFUser){
        self.dismissViewControllerAnimated(true, completion: nil)
    }

    func logInViewController(logInController: PFLogInViewController, didFailToLogInWithError error: NSError?){
        let alertLoginFailed = UIAlertController(title: "Login Failed", message: "Your username or password is invalid!", preferredStyle: UIAlertControllerStyle.Alert)
        alertLoginFailed.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alertLoginFailed, animated: true, completion: nil)
        print("Login failed.........!")
    }

    func signUpViewController(signUpController: PFSignUpViewController, didSignUpUser user: PFUser){
        self.dismissViewControllerAnimated(true, completion: nil)
    }

    func signUpViewController(signUpController: PFSignUpViewController, didFailToSignUpWithError error: NSError?){
        print("Sign up failed.........!")
    }

    func setupLoginView(){
        if(PFUser.currentUser() == nil){
            let loginViewController = PFLogInViewController()
            loginViewController.delegate = self
            let signUpViewController = PFSignUpViewController()
            signUpViewController.delegate = self
            loginViewController.logInView!.logo = UIImageView(image: UIImage(named:"logo.png"))

            loginViewController.signUpController = signUpViewController
            self.presentViewController(loginViewController, animated: true, completion: nil)
        }else{
            print("login as: " + PFUser.currentUser()!.username!)
            //prepare new view here
        }

    }
}

refer this answer http://stackoverflow.com/questions/11862883/whose-view-is-not-in-the-window-hierarchy — Rizwan Shaikh, Oct 02 '15 at 07:27
Could it be because your viewController is not on screen when the loginViewController delegate didFailToLogInWithError is called? — Azzaknight, Oct 02 '15 at 09:53
try logInContorller.presentViewController instead of self.presentViewController — Azzaknight, Oct 02 '15 at 09:54

joern · Answer 1 · 2015-10-02T18:15:42.787

You have to call presentViewController:animated:completion on your login view controller.

Here is a simplified version of your class to show you what I mean:

class ViewController: UIViewController {
    weak var loginViewController: UIViewController?

    func setupLoginViewController() {
        let loginVC = PFLogInViewController()
        // setup loginVC
        loginViewController = loginVC // store the reference
    }

    func loginDidFail() {
        let alertVC = UIAlertController(...)
        // setup alertVC
        loginViewController?.presentViewController(...) // present the alert from the login view controller
    }
}

No problem! Please be so kind to mark one of the answers as "accepted" , so this question is marked as answered. — joern, Oct 07 '15 at 10:19

score 0 · Answer 2 · answered Oct 02 '15 at 10:03

when

func logInViewController(logInController: PFLogInViewController, didFailToLogInWithError error: NSError?){
        let alertLoginFailed = UIAlertController(title: "Login Failed", message: "Your username or password is invalid!", preferredStyle: UIAlertControllerStyle.Alert)
        alertLoginFailed.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alertLoginFailed, animated: true, completion: nil)
        print("Login failed.........!")
    }

is called, your view controller is not on screen. Therefore you could either

dismiss the logInViewController, then display the alert and pass setUpLogInView as the handler.
or in the above function, try logInController.presentViewController instead of self.presentViewController

score 0 · Answer 3 · edited May 23 '17 at 11:59

0

I had the same problem in Objective-C, it occurs when the parent window has not yet been drawn to the screen. I solved the problem by calling the code from within viewDidAppear rather than viewDidLoad. See UIAlert error, whose view is not in the window hierarchy

edited May 23 '17 at 11:59

Community

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answered Dec 09 '15 at 10:15

Steve

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UIAlertController whose view is not in the window hierarchy

3 Answers3