每次在嵌套条件swift ios中都会弹出AlertController [英] AlertController is being popped every time in nested conditions swift ios

问题描述

我已经定义了一个alertcontroller，当用户名或密码不正确时，警报应该弹出，并且它正常工作。但是当用户名和&密码是匹配的，尽管匹配它每次登录时弹出。我想我没有以正确的方式定义嵌套条件？帮助我对多个嵌套条件进行排序。

I have defined an alertcontroller when username or password is not correct the alert should pop, and it is working fine. but when the username & password is matched despite matching it pops up everytime when log in. I think I have not defined nested condition in a right way? help me to sort the multiple nested condition.

登录代码

import UIKit
import CoreData
import Foundation

 class ViewController: UIViewController {

var usernameGlobal : String = ""

@IBOutlet weak var emailText: UITextField!
@IBOutlet weak var passText: UITextField!

@IBOutlet weak var loginButton: UIButton!
@IBAction func loginAction(_ sender: Any) {

    let appDel = UIApplication.shared.delegate as! AppDelegate
    let context = appDel.persistentContainer.viewContext

    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
        request.returnsObjectsAsFaults = false
      //  request.predicate = NSPredicate(format: "username = %@", "" + emailText.text!)


    do {

    let results = try! context.fetch(request)

        if(results.count > 0){

            for result in results as! [NSManagedObject]
            {


                if  emailText.text == result.value(forKey: "username") as? String && passText.text == result.value(forKey: "password") as? String {
                    print(emailText.text!, passText.text!)
                    usernameGlobal = self.emailText.text!
                    let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle : nil)
                    let desController = mainStoryBoard.instantiateViewController(withIdentifier: "AddViewController") as! AddViewController
                    let newFrontViewController = UINavigationController.init(rootViewController:desController)
                    revealViewController().pushFrontViewController(newFrontViewController, animated: true)

                }

                else {

                       let alertController = UIAlertController(title: "Oops!", message: "Incorrect username or password", preferredStyle: .alert)

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

                        present(alertController, animated: true, completion: nil)
                    }

            }

            }
        }
    }



@IBAction func signupSegue(_ sender: Any) {

    let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle : nil)
    let desController = mainStoryBoard.instantiateViewController(withIdentifier: "SignupViewController") as! SignupViewController
    let newFrontViewController = UINavigationController.init(rootViewController:desController)
    revealViewController().pushFrontViewController(newFrontViewController, animated: true)

}


override func viewDidLoad() {
    super.viewDidLoad()

    loginButton.backgroundColor = UIColor.blue

}

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


}

推荐答案

您可以使用以下代码：

@IBAction func loginAction(_ sender: Any) {

        let appDel = UIApplication.shared.delegate as! AppDelegate
        let context = appDel.persistentContainer.viewContext
        let isMatched = false
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
        request.returnsObjectsAsFaults = false

         do {

            let results = try! context.fetch(request)

            if(results.count > 0){

                for result in results as! [NSManagedObject]
                {


                    if  emailText.text == result.value(forKey: "username") as? String && passText.text == result.value(forKey: "password") as? String {
                        print(emailText.text!, passText.text!)
                        usernameGlobal = self.emailText.text!
                        let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle : nil)
                        let desController = mainStoryBoard.instantiateViewController(withIdentifier: "AddViewController") as! AddViewController
                        let newFrontViewController = UINavigationController.init(rootViewController:desController)
                        revealViewController().pushFrontViewController(newFrontViewController, animated: true)
                        isMatched = true
                        break

                    }

                }

                if !isMatched {

                      let alertController = UIAlertController(title: "Oops!", message: "Incorrect username or password", preferredStyle: .alert)
                      let defaultAction = UIAlertAction(title: "OK", style: .default, handler: nil)
                      alertController.addAction(defaultAction)

                      present(alertController, animated: true, completion: nil)
                 }

            }
        }
    }

变化：

你添加

        let isMatched = false

在if条件中添加 break 语句。因此，一旦用户名和密码匹配，它就会打破循环。然后在for循环检查之后检查isMatched是否为false，然后显示结果。

You add break statement in if condition. So that it breaks the loop once username and password is matched. Then after for loop check if the isMatched is false, then show the result.

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