Question

我的应用程序的初始视图控制器是HomeView，它显示对用户重要的信息。如果用户未登录，则用户界面将显示LoginView视图控制器，提示用户登录。

问题是，当用户输入错误的登录凭据，点击登录时，应用程序会显示错误。一旦错误被清除，应用程序将解除LoginView，然后再次显示LoginView。行为应该只是警报然后离开LoginView。

1）从HomeView（初始视图控制器）

override func viewWillAppear(animated: Bool) {

    if (PFUser.currentUser()?.username == nil) {
        dispatch_async(dispatch_get_main_queue(), { () -> Void in

            let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("LoginView")

            //self.showViewController(viewController, sender: self)

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

        })
    }
}

2）从LoginView验证用户凭据，然后使用解析登录尝试。

@IBAction func loginButton(sender: AnyObject) {

    let username = usernameField.text?.lowercaseString

    let password = passwordField.text

    if username == "" || password == "" {

        displayAlert("Error in form", message: "Please enter a username and password")

    } else if username?.characters.count < 5 {

        self.displayAlert("Failed Signup", message: "Username must be greater than 5 characters")

    } else if password?.characters.count < 8 {

        self.displayAlert("Failed Signup", message: "Password must be greater than 8 characters")

    } else {

        activityIndicator = UIActivityIndicatorView(frame: CGRectMake(0, 0, 50, 50))

        activityIndicator.center = self.view.center

        activityIndicator.hidesWhenStopped = true

        activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.Gray

        view.addSubview(activityIndicator)

        activityIndicator.startAnimating()

        UIApplication.sharedApplication().beginIgnoringInteractionEvents()

        PFUser.logInWithUsernameInBackground(username!, password: password!, block: { (user, error) -> Void in

            //Kill spinner
            self.activityIndicator.stopAnimating()

            UIApplication.sharedApplication().endIgnoringInteractionEvents()

            if ((user) != nil) {

                dispatch_async(dispatch_get_main_queue(), { () -> Void in

                    let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("HomeView")

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

            } else {

                self.displayAlert("Failed Signup", message: "\(error)")

            }
        })
    }
}

编辑：

3）displayAlert Function

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

    let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
    alert.addAction((UIAlertAction(title: "OK", style: .Default, handler: { (action) -> Void in

        self.dismissViewControllerAnimated(true, completion: nil)

    })))

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

}

我应该注意到我的家庭视图控制器是带有侧边栏菜单的SWRevealViewController的一部分。 SWRevealViewController的导航控制器作为初始视图控制器

Answer 1

您需要在完成按钮时删除对self.dismissViewController的调用。这就是告诉应用程序解除登录视图的原因。在设计仅出现错误并且您希望关闭按钮删除警报的警报时，您不必在完成时放置任何代码。

登录屏幕被取消，并在登录失败时重新出现

1 个答案: