ios - 在通过代码呈现的另一个 ViewController 上呈现 AlertController

Question

我通过空 VC 上的代码实例化了 Parse 的常用 UI 登录屏幕。如果未验证用户的电子邮件，我想显示一个 AlertController。因此，我将通过代码创建的 logInViewController 来呈现 AlertController...我理解 AlertController 不在窗口层次结构中的错误，但我不确定如何解决它。如果我关闭 logInViewController 但我不想这样做，它会起作用，我希望它存在于后台。使用 swift 。

这个答案没有找到确切的问题:AlertController is not in the window hierarchy

override func viewDidAppear(animated: Bool) {

        super.viewDidAppear(animated)
        if (PFUser.currentUser() == nil) {

            //build logInVC in Code:
            var logInViewController = PFLogInViewController()

            var logInLogoTitle = UILabel()

            logInLogoTitle.text = "Thredz"

            logInLogoTitle.font = UIFont(name: "Cochin", size: 40.0)

            logInViewController.fields = PFLogInFields.UsernameAndPassword | PFLogInFields.LogInButton | PFLogInFields.SignUpButton | PFLogInFields.PasswordForgotten | PFLogInFields.Twitter

            logInViewController.logInView?.backgroundColor = UIColor.whiteColor()

            logInViewController.logInView?.logo = logInLogoTitle

            logInViewController.delegate = self

            //present log in VC
            self.presentViewController(logInViewController, animated: true, completion: nil)

            //build signUpViewController
            var signUpViewController = PFSignUpViewController()

            signUpViewController.delegate = self

            var signUpLogoTitle = UILabel()

            signUpLogoTitle.text = "Thredz"

            signUpViewController.signUpView?.logo = signUpLogoTitle

            logInViewController.signUpController = signUpViewController

        }


    }



  func logInViewController(logInController: PFLogInViewController, didLogInUser user: PFUser) {


        if (PFTwitterUtils.isLinkedWithUser(user)) {
            var twitterUsername = PFTwitterUtils.twitter()?.screenName

            PFUser.currentUser()?.username = twitterUsername

            PFUser.currentUser()?.saveEventually(nil)

        }

        if user["emailVerified"] as! Bool == true {
            dispatch_async(dispatch_get_main_queue()) {
                self.performSegueWithIdentifier(self.peopleTableViewControllerSegue, sender: nil)
            }
        } else {
            // User needs to verify email address before continuing
            let alertController = UIAlertController(
                title: "Email address verification",
                message: "We have sent you an email that contains a link - you must click this link before you can continue.",
                preferredStyle: UIAlertControllerStyle.Alert
            )
            alertController.addAction(UIAlertAction(title: "OK",
                style: UIAlertActionStyle.Default,
                handler: nil)
            )

            self.presentViewController(alertController, animated: true, completion: nil)
        }

    }

Answer 1

在您的 logInViewController(logInController:didLogInUser:) 函数中，更改行

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

到

logInController.presentViewController(alertController, animated: true, completion: nil)

这将在登录 Controller 的顶部显示警报 Controller ，而不是空的 View Controller 。