ios - 推送到另一个 ViewController

Question

我在推送到另一个 View Controller 时遇到问题。我创建了一个简单的登录系统，但问题是即使密码错误，它也会将我推送到默认 View Controller 。

import UIKit
import Parse

class ViewController: UIViewController {

@IBOutlet weak var usernameTextField: UITextField!
@IBOutlet weak var passwordTextField: UITextField!

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

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

    alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (alert) in

    }))
    self.present(alert, animated: true, completion: nil)

}

@IBAction func loginButton(_ sender: Any) {

    // ************ Login Page ************

    // Username error checking

    if usernameTextField.text == "" {

        let usernameAlert = UIAlertController(title: "Username is missing", message: "Please enter your username", preferredStyle: UIAlertControllerStyle.alert)

        usernameAlert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (action) in
            }))
        self.present(usernameAlert, animated: true, completion: nil)

        // Password error checking

    } else {

        if passwordTextField.text == "" {

            let passwordAlert = UIAlertController(title: "Passwors is missing", message: "Please enter your password", preferredStyle: UIAlertControllerStyle.alert)

            passwordAlert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (action) in
                self.dismiss(animated: true, completion: nil)
            }))
            self.present(passwordAlert, animated: true, completion: nil)            }

        else {

        PFUser.logInWithUsername(inBackground: usernameTextField.text!, password: passwordTextField.text!, block: { (user, error) in

            if error != nil {



                var displayErrorMessage = "Please try again later."

                if let errorMessage = error as NSError? {

                    displayErrorMessage = errorMessage.userInfo["error"] as! String

                }


                self.createAlert(title: "Login Error", message: displayErrorMessage)
            } else {

                print ("Logged in")

                let storyBoard = UIStoryboard(name: "Main", bundle: nil)

                let cameraVC = storyBoard.instantiateViewController(withIdentifier: "CameraViewController") as! CameraViewController

                self.navigationController?.pushViewController(cameraVC, animated: true)

            }
            })
        }
    }

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



        }

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

注意:当用户名和密码有效时，我在调试区域收到“已登录”消息。

Answer 1

您是否在直接按钮中给出了 segue 连接，例如

so it wont check the condition if you click the button it directly segue to another VC.

如果使用的是storyboard ID则去掉VC之间的连接，可以直接访问

 let storyBoard = UIStoryboard(name: "Main", bundle: nil)

            let cameraVC = storyBoard.instantiateViewController(withIdentifier: "CameraViewController") as! CameraViewController

            self.navigationController?.pushViewController(cameraVC, animated: true)

其他

connection oriented segue using direclty class

 [self performSegueWithIdentifier:@"identifierName" sender:self];

调用类似

else {

            print ("Logged in")
            performSegue(withIdentifier: "identifierName", sender: self)

            }