CODEWITHSUNDEEP
swiftswift2uialertcontroller
Thanh Tran
Thanh Tran

Reputation: 45

UIAlertController whose view is not in the window hierarchy

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
        }

    }
}

Upvotes: 2

Views: 3098

Answers (3)

Steve
Steve

Reputation: 303

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

Upvotes: 0

joern
joern

Reputation: 27620

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
    }
}

Upvotes: 0

Azzaknight
Azzaknight

Reputation: 167

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

Upvotes: 0

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