从视图控制器的分离文件中呈现视图控制器

Question

我有这个应用程序，它使用 Alamofire 向后端发送请求，该后端会返回响应，并根据响应执行操作。我发现 Alamofire 代码对于我的项目来说太混乱了，我想将代码解析为一行代码。为此，我将 Alamofire 代码块放在我的一个自定义框架库中的一个名为 Requests 的类中。每次我从后端收到响应时，我都想运行一个函数（不是问题），然后执行 segue/present/push 到下一个视图控制器（问题）。

假设我有一个 Request 类，其中包含一个 login() 函数，该函数接受用户名和密码参数。调用此函数时的一行代码如下所示：Request.login(username, password) 和最终Request.logout() 等。此函数可以在同一个 Xcode 项目中的 ACommonLibrary 框架中找到。这将运行 Alamofire 代码以发送请求，然后以 JSON 格式获得“authenticated: true”响应，并据此应用程序将 segue/present/push 到 Profile 视图控制器。

我尝试使用布尔值执行此操作，如果我收到响应，变量将从 false 设置为 true 并由函数返回，因此我可以在 if/else 语句中使用它，但这不起作用。我用

正常尝试过

let storyboard:UIStoryboard = UIStoryboard(name: "login", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "Login") as! LoginViewController
self.present(vc, animated: true, completion: nil)

但我得到实例成员“当前”不能用于类型“请求” 然后我发现有人问How to present a view controller from a detached view controller?，但这也没有用，假设是因为我在一个故事板中有多个视图控制器。

我搜索了这个错误和其他类似的错误，但无济于事。所以现在我质疑这是否可能实现，或者我必须以不同的方式处理它？任何建议都值得赞赏。提前致谢。

编辑：在下面添加了代码。

主要
-> 登录
-> -> LoginViewController.swift

class LoginViewController: UIViewController {

    @IBOutlet weak var usernameTextField: CustomTextField!
    @IBOutlet weak var passwordTextField: CustomTextField!
    @IBOutlet weak var loginButton: UIButton!
    @IBOutlet weak var forgotPasswordButton: UIButton!
    @IBOutlet weak var navigationBar: UINavigationBar!

    override func viewWillAppear(_ animated: Bool) {
        UIApplication.shared.statusBarStyle = .lightContent
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // MARK: - IBActions
    @IBAction func loginPressed(sender: AnyObject) {
        usernameTextField.trimSpaces()

        let username = usernameTextField.text!
        let password = passwordTextField.text!

        Request.login(username, password)
    }
}

公共图书馆
-> 后端
-> -> 请求.swift

public class Request {
    public class func login(_ username:String, _ password:String) {

    let headers: HTTPHeaders = [
        "Content-Type": "application/x-www-form-urlencoded"
    ]

    let parameters:Parameters = [
        "username": username,
        "password": password
    ]

    let endpoint = GlobalVariables.BaseURLString + "login"

    Alamofire.request(endpoint, method: .post, parameters: parameters, headers: headers)
    .responseJSON { response in
        switch response.result {
            case .success/*(let data)*/:
            if response.result.value != nil{
                let swiftyJsonVar = JSON(response.result.value!)

                let responseSuccess = swiftyJsonVar["success"]
                let responseMessage = swiftyJsonVar["error_message"]
                let responseSession = swiftyJsonVar["session_id"]
                let responseUserId = swiftyJsonVar["user_id"]

            if responseSession != JSON.null {
                GlobalVariables.Keychain["user_id"] = responseUserId.rawValue as? String
                GlobalVariables.Keychain["session_id"] =  responseSession.rawValue as? String
                try? GlobalVariables.Keychain.set(username, key: "username")

                if responseSuccess.boolValue {
                    let storyboard:UIStoryboard = UIStoryboard(name: "profile", bundle: nil)
                    let vc = storyboard.instantiateViewController(withIdentifier: "ProfileNavigation") as!     ProfileViewController
                    self.present(vc, animated: true, completion: nil)
                }else{
                    SCLAlertView().showNotice("Warning!", subTitle: responseMessage.stringValue)
                }
            }else{
                SCLAlertView().showError("Error logging in", subTitle: "There was an error while logging in     to your account. If this error persists, the server is down :D ")
            }
        }
        case .failure/*(let err)*/:
//          NSLog("------------------DATA START-------------------")
//          NSLog("Response String: (String(describing: err))")
            SCLAlertView().showError("Error logging in", subTitle: "There was an error while logging in to     your account. If this error persists, the server is down :D ")
//          NSLog("------------------DATA END-------------------")
        }
    }
}    

Answer 1

首先您应该知道self 在您尝试在Requests 类的login 方法中执行的类方法中是不可访问的。您尝试做的事情有两种可能，如下所述。

1. Requests 不是UIViewController 的子类。只有UIViewController 或其子类可以呈现另一个视图控制器。因此可以使用共享应用程序的keyWindow 和rootViewController。方法如下：

   if responseSuccess.boolValue {
       let storyboard:UIStoryboard = UIStoryboard(name: "profile", bundle: nil)
       let vc = storyboard.instantiateViewController(withIdentifier: "ProfileNavigation") as! ProfileViewController
       let rootVC = UIApplication.shared.keyWindow?.rootViewController
       rootVC?.present(vc, animated: true, completion: nil)
   } else {
       SCLAlertView().showNotice("Warning!", subTitle: responseMessage.stringValue)
   }
   

2. 在进行异步网络调用的方法中使用闭包，就像在 login 方法中所做的那样。然后在闭包中执行 segues 和显示/呈现视图控制器。方法如下：

   public class Request {
   public class func login(_ username:String, _ password:String, withSuccess successHandler:@escaping (Bool) -> Void, andFailure failureHandler:@escaping (String) -> Void) {
   
       let headers: HTTPHeaders = ["Content-Type": "application/x-www-form-urlencoded"]
   
       let parameters:Parameters = ["username": username, "password": password]
   
       let endpoint = GlobalVariables.BaseURLString + "login"
   
       Alamofire.request(endpoint, method: .post, parameters: parameters, headers: headers)
           .responseJSON { response in
               switch response.result {
               case .success/*(let data)*/:
                   if response.result.value != nil{
                       let swiftyJsonVar = JSON(response.result.value!)
   
                       let responseSuccess = swiftyJsonVar["success"]
                       let responseMessage = swiftyJsonVar["error_message"]
                       let responseSession = swiftyJsonVar["session_id"]
                       let responseUserId = swiftyJsonVar["user_id"]
   
                       if responseSession != JSON.null {
                           GlobalVariables.Keychain["user_id"] = responseUserId.rawValue as? String
                           GlobalVariables.Keychain["session_id"] =  responseSession.rawValue as? String
                           try? GlobalVariables.Keychain.set(username, key: "username")
   
                           if responseSuccess.boolValue {
                               successHandler(true)
                           } else {
                               failureHandler(responseMessage.stringValue)
                           }
                       } else {
                           failureHandler("There was an error while logging in to your account. If this error persists, the server is down :D")
                       }
                   }
               case .failure/*(let err)*/:
                   failureHandler("There was an error while logging in to your account. If this error persists, the server is down :D")
               }
           }
       }
   }
   

   然后在LoginViewController

   @IBAction func loginPressed(sender: AnyObject) {
       usernameTextField.trimSpaces()
   
       let username = usernameTextField.text!
       let password = passwordTextField.text!
   
       Request.login(username,
                     password,
                     withSuccess: { (success) in
                       let vc = self.storyboard?.instantiateViewController(withIdentifier: "ProfileViewController") as! ProfileViewController
                       self.present(vc, animated: true, completion: nil)
       }) { (errorMsg) in
           SCLAlertView().showError("Error logging in", subTitle: errorMsg)
       }
   }