Segue和displayMessage函数不起作用 - Swift 3/4

Question

用户注册代码。当用户注册时，它应该转到新的视图控制器（在这种情况下为主页），如果用户名已经存在，则注册时应显示消息：已存在。

这是代码。没错。用户已正确注册，如果用户名已存在，则返回api的错误响应。只是事情是它没有按要求显示警报信息，并且如果注册则不会显示。显示“所有字段都是必填项”和“请确保密码匹配”，仅显示“已存在”。

import UIKit
import SwiftyJSON
import Alamofire
import SwiftKeychainWrapper

class RegisterUserViewController: UIViewController {
    @IBOutlet weak var firstNameTextField: UITextField!
    @IBOutlet weak var lastNameTextField: UITextField!
    @IBOutlet weak var emailAddressTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!
    @IBOutlet weak var repeatPasswordTextField: 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 cancelButtonTapped(_ sender: Any) {
        print("Cancel button tapped")

        self.dismiss(animated: true, completion: nil)
    }


    @IBAction func signupButtonTapped(_ sender: Any) {
       print("Sign up button tapped")


        // Validate required fields are not empty
        if (firstNameTextField.text?.isEmpty)! ||
            (lastNameTextField.text?.isEmpty)! ||
            (emailAddressTextField.text?.isEmpty)! ||
            (passwordTextField.text?.isEmpty)!
        {
            // Display Alert message and return
            displayMessage(userMessage: "All fields are quired to fill in")
            return
        }

        // Validate password
        if ((passwordTextField.text?.elementsEqual(repeatPasswordTextField.text!))! != true)
        {
            // Display alert message and return
            displayMessage(userMessage: "Please make sure that passwords match")
            return
        }


        let params = [

            "first_name"      :  firstNameTextField.text! as Any,
            "last_name"       :  lastNameTextField.text! as Any,
            "email_id"        :  emailAddressTextField.text! as Any,
            "password"        :  passwordTextField.text! as Any,

            ]


        Alamofire.SessionManager.default.request("http://horn.hostingduty.com/api/v1/app_adduser", method: .post, parameters: params, encoding: URLEncoding(destination: .methodDependent))
            .validate(statusCode: [200, 201])
            .responseJSON
            {
                [unowned self] (response) in



                switch(response.result)
                {
                case .success:
                    guard let json = response.result.value as!
                        [String:Any]? else{ return}
                    print("Response \(json)")
                    if let data = json["data"] as! [String:Any]?
                    {
                        let email_id : String = self.emailAddressTextField.text!
                        let userdefault = UserDefaults.standard
                        userdefault.set(self.emailAddressTextField.text, forKey: "email_id")
                        print(email_id)
                        UserDefaults.standard.synchronize()


                        DispatchQueue.main.async
                        {

                    let homePage = self.storyboard?.instantiateViewController(withIdentifier: "HomePageViewController") as! SWRevealViewController
                    let appDelegate = UIApplication.shared.delegate
                    appDelegate?.window??.rootViewController = homePage
                        }

                    }

                case .failure:

                        DispatchQueue.main.async
                            {
                        self.displayMessage(userMessage: "Already exists !! ")
                        return
                            }
                }
        }



    }



    func displayMessage(userMessage:String) -> Void {
        DispatchQueue.main.async
            {}
                let alertController = UIAlertController(title: "Alert", message: userMessage, preferredStyle: .alert)

                let OKAction = UIAlertAction(title: "OK", style: .default) { (action:UIAlertAction!) in
                    // Code in this block will trigger when OK button tapped.
                    print("Ok button tapped")
                    DispatchQueue.main.async
                        {
                            self.dismiss(animated: true, completion: nil)
                    }
                }
                alertController.addAction(OKAction)
                self.present(alertController, animated: true, completion:nil)
        }

}

Answer 1

Alamofire.SessionManager.default.request("http://horn.hostingduty.com/api/v1/app_adduser", method: .post, parameters: params, encoding: URLEncoding(destination: .methodDependent))
        .validate(statusCode: [200, 201])
        .responseJSON
        {
            [weak self] (response) in
            guard let sSelf = self else { return }


            switch(response.result)
            {
            case .success:
                guard let json = response.result.value as!
                    [String:Any]? else{ return}
                print("Response \(json)")
                if let data = json["data"] as! [String:Any]?
                {
                    let email_id : String = self.emailAddressTextField.text!
                    let userdefault = UserDefaults.standard
                    userdefault.set(self.emailAddressTextField.text, forKey: "email_id")
                    print(email_id)
                    UserDefaults.standard.synchronize()


                    DispatchQueue.main.async
                    {

                let homePage = sSelf.instantiateViewController(withIdentifier: "HomePageViewController") as! SWRevealViewController
                let appDelegate = UIApplication.shared.delegate
                appDelegate?.window??.rootViewController = homePage
                    }

                }

            case .failure:

                    DispatchQueue.main.async
                        {
                    sSelf.displayMessage(userMessage: "Already exists !! ")
                    return
                        }
            }
    }

而不是无主的自我，对自我的弱引用，然后尝试在完成处理程序中获得它的强引用

我还想指出，api电话的失败也可能是因为其他原因。您不能总是假设故障是由于系统中已存在用户而引起的

所以尝试使用http响应状态代码，否则，

做出像成功一样的事情

{

"code" : "0001", 
"msg" :  "",
"your custom object key here" : {


}
}

并且失败了

{

"code" : "0000",  // "0000" code can be "0002" if user already exist
"msg" :  "reason for failure",

  }

在成功的情况下，检查“代码”值