Swift - 关闭警报消息关闭视图控制器

Posted 2023-02-23

【中文标题】Swift - 关闭警报消息关闭视图控制器

【英文标题】：Swift - Dismissing Alert Message Closes View Controller

【发布时间】：2015-04-14 14:52:00

【问题描述】：

我有一个注册过程，其中我有一个登录/注册 Facebook 的入口点（连接到 Parse）。如果用户从未注册过他们的 Facebook 帐户，那么他们将被发送到用户注册用户名、电子邮件和密码的发送页面。我有一个功能设置，如果用户将任何文本字段留空以进行用户注册，则会出现一条警报消息，并显示该字段为空白的错误。此功能正常工作，但是当我单击“确定”关闭消息时，注册视图控制器会自行关闭并显示入口点（登录屏幕）视图控制器。这不应该发生，我没有从注册屏幕到登录屏幕的 segue 设置。有什么想法吗？

我突然想到的一件事是控制台日志中的错误，我认为这实际上与 Parse if/else 语句有关，而不是与 field == nil 语句有关。

控制台日志：

2015-04-14 10:42:56.293 tappery[574:142525] [Error]: missing username (Code: 200, Version: 1.6.3)

登录屏幕视图控制器：

import UIKit

class LoginViewController: UIViewController 


    @IBOutlet var loginCancelledLabel: UILabel!

    override func viewDidLoad() 
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        var currentUser = PFUser.currentUser()

        if currentUser != nil 
            println("User is Logged in")
         else 
            println("User is not logged in")
        

    

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


    @IBAction func facebookLoginButton(sender: AnyObject) 

        var permissions = ["public_profile", "email", "user_friends"]

        self.loginCancelledLabel.alpha = 0

        PFFacebookUtils.logInWithPermissions(permissions, 
            (user: PFUser!, error: NSError!) -> Void in
            if let user = user 
                if user.isNew 
                    println("User signed up and logged in through Facebook!")

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

                 else 
                    println("User logged in through Facebook!")

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

                
             else 
                println("Uh oh. The user cancelled the Facebook login.")

                self.loginCancelledLabel.alpha = 1

            
        )


    

注册视图控制器：

import UIKit

class UserRegistrationViewController: UIViewController 


    func displayAlert(title:String, error:String) 

        var alert = UIAlertController(title: title, message: error, preferredStyle: UIAlertControllerStyle.Alert)

        alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: 
            action in

            self.dismissViewControllerAnimated(true, completion: nil)


        ))

        self.presentViewController(alert, animated: true, completion: nil)


    

    @IBOutlet var usernameTextField: UITextField!

    @IBOutlet var emailTextField: UITextField!

    @IBOutlet var passwordTextField: UITextField!


    override func viewDidLoad() 
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    

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


    @IBAction func registerUser(sender: AnyObject) 

        var error = ""

        if usernameTextField.text == nil || emailTextField.text == nil || passwordTextField.text == nil 

            error = "Please enter a username, email and password"

        


        if error != "" 

            displayAlert("Error In Form", error: error)

         else 

            var user = PFUser.currentUser()

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

            user.saveInBackgroundWithBlock 
                (succeeded: Bool!, signupError: NSError!) -> Void in
                if signupError == nil 

                    println(user.username)
                    println(user.password)
                    println(user.email)


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

                    // Hooray! Let them use the app now.
                 else 

                    if let errorString = signupError.userInfo?["error"] as? NSString 
                        error = errorString
                     else 

                        error = "Please try again later."

                    


                    self.displayAlert("Could Not Sign Up", error: error)

                
            


        


    

【参考方案1】：

从您的“确定”按钮UIAlertAction 的handler 中删除self.dismissViewControllerAnimated(true, completion: nil)。单击确定按钮后，警报会自动解除，并且您正在通过此调用解除注册控制器。