在swift中启动segue的问题

Question

我遇到了一些让segue正常工作的问题。

其他一切正常，比如保存用户名和密码进行解析。但是当用户按下sign up或log in时，segue不起作用。

这是我的代码：

import UIKit
import Parse

class ViewController: UIViewController {

// Declaring variables & functions
var signupMode = true

var acitivityIndicator = UIActivityIndicatorView()

func displayAlert (title: String, message: String) {

    let alertController = UIAlertController(title: title, message: title, preferredStyle: .alert)

    alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))

    self.present(alertController, animated: true, completion: nil)


}


// First view controller outlets/actions
@IBOutlet var signupButton: UIButton!
@IBOutlet var loginButton: UIButton!

@IBOutlet var emailTextField: UITextField!
@IBOutlet var passwordTextField: UITextField!

@IBAction func signupAction(_ sender: AnyObject) {

    if emailTextField.text == "" && passwordTextField.text == "" {

        displayAlert(title: "Error in form", message: "Please enter both an email and password")

    } else {

        acitivityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
        acitivityIndicator.center = self.view.center
        acitivityIndicator.hidesWhenStopped = true
        acitivityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
        view.addSubview(acitivityIndicator)
        acitivityIndicator.startAnimating()
        UIApplication.shared().beginIgnoringInteractionEvents()

        if signupMode {

            // Sign Up

            let user = PFUser()

            user.username = emailTextField.text
            user.password = passwordTextField.text

            user.signUpInBackground(block: { (success, error) in

                self.acitivityIndicator.stopAnimating()
                UIApplication.shared().endIgnoringInteractionEvents()

                if error != nil {

                    var displayErrorMessage = "Please try again later."

                    if let errorMessage = error?.userInfo["error"] as? String {

                        displayErrorMessage = errorMessage

                    }

                    self.displayAlert(title: "Signup Error", message: displayErrorMessage)

                } else {

                    print("user signed up")

                    self.performSegue(withIdentifier: "HomePageViewController", sender: self)
                }


            })


        }


        }

    }


@IBAction func loginAction(_ sender: AnyObject) {

    acitivityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
    acitivityIndicator.center = self.view.center
    acitivityIndicator.hidesWhenStopped = true
    acitivityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
    view.addSubview(acitivityIndicator)
    acitivityIndicator.startAnimating()
    UIApplication.shared().beginIgnoringInteractionEvents()

    let userEmail = self.emailTextField.text

    let userPassword = self.passwordTextField.text

    PFUser.logInWithUsername(inBackground: userEmail!, password:userPassword!) {
        (user: PFUser?, error: NSError?) -> Void in
        if user != nil {

                self.performSegue(withIdentifier: "HomePageViewController", sender: self)

        } else {

            self.acitivityIndicator.stopAnimating()

            }
        }

    }

Answer 1

尝试在主线程中进行segue

dispatch_async(dispatch_get_main_queue()) {
   self.performSegue(withIdentifier: "HomePageViewController", sender: self)
}