如何在swift 3中逐步等待核心数据添加功能

Question

我有coredata 表，当用户登录时想要在其中插入大数据。我有核心数据添加功能，我有 PKHUD 加载我尝试使用它们，但功能 不要等待 完成所有数据插入，进入 Profile viewcontroller，我想在核心数据添加时等待功能完成PKHUD加载后继续..我该如何解决？ 我的代码在下面。

       @IBAction func login (sender: UIButton){

         if prefs.string(forKey: "name") == "John"{
  }else{ 
   if prefs.string(forKey: "adddata") == "yes"{

        // LOADING BAR STARDED
         PKHUD.sharedHUD.contentView = PKHUDProgressView()
         PKHUD.sharedHUD.show()

         // HERE MY ADD CORE DATA FUNCTIONS
         coreDataAdd(where : "User")
         coreDataAdd(where : "Profile")
         coreDataAdd(where : "Games")


 if prefs.string(forKey: "go") == "yes"{

        let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
                                        let nextViewController = storyBoard.instantiateViewController(withIdentifier: "Profile") as! profileViewController
                                        self.present(nextViewController, animated:true, completion:nil)

}

      // LOADING BAR END
      DispatchQueue.main.async {
         PKHUD.sharedHUD.hide(animated:false);
          }
}

}
}

下面是我的功能

 func coreDataAdd(where : String) {


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

        let parameters = [
            "user": "\(prefs.string(forKey: "user")!)"
            ] as [String : String]
        Alamofire.request(geturl, method: .post, parameters: parameters, encoding: URLEncoding.httpBody, headers: headers)
            .responseData{ response in
                let json = JSON(data:response.result.value!)  
                let success = json["Success"]["status"].boolValue
                let addJson = json["\(where)_list"].array

                if success == true {

                    if where == "User" {
                   for users in addJson! {
                           let addUser =  NSEntityDescription.insertNewObject(forEntityName: "\(where)", into:context) as! User
                            addUser.id = users["id"].int32Value
                            addUser.name = users["name"].stringValue
                            (UIApplication.shared.delegate as! AppDelegate).saveContext()
                     }

                    }



                }else{


                }
                  }

    }

Answer 1

尝试为您的函数使用完成处理程序，或者可以尝试使用依赖等待的操作队列

    coreDataAdd (where : "User", onCompletion: { (isFinished) in
       if isFinished {
          coreDataAdd (where : "Profile", onCompletion: { (isFinished) in
          if isFinished { 
          coreDataAdd (where : "Profile", onCompletion: { (isFinished) in
            if isFinished
            //Here segue to the next view
            let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
                                    let nextViewController = storyBoard.instantiateViewController(withIdentifier: "Profile") as! profileViewController
                                    self.present(nextViewController, animated:true, completion:nil)

       })
       } 
       }

       })
    })



    func coreDataAdd(where : String, onCompletion: @escaping (Bool) -> Void) {


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

    let parameters = [
        "user": "\(prefs.string(forKey: "user")!)"
        ] as [String : String]
    Alamofire.request(geturl, method: .post, parameters: parameters, encoding: URLEncoding.httpBody, headers: headers)
        .responseData{ response in
            let json = JSON(data:response.result.value!)  
            let success = json["Success"]["status"].boolValue
            let addJson = json["\(where)_list"].array

            if success == true {

                if where == "User" {
               for users in addJson! {
                       let addUser =  NSEntityDescription.insertNewObject(forEntityName: "\(where)", into:context) as! User
                        addUser.id = users["id"].int32Value
                        addUser.name = users["name"].stringValue
                        (UIApplication.shared.delegate as! AppDelegate).saveContext()

                 } 
                onCompletion(true)
                }



            }else{


            }
              }

}

Answer 2

使用NSFetchedResultsController 它将跟踪核心数据的变化，并有委托回调告诉您何时更改您的表格视图。

Answer 3

这里的问题是您在 coreDataAdd 方法中进行异步调用（因为它们应该是网络调用）。您的要求是在每次网络调用完成后停止 PKHUD 加载程序。

您可以为此目的使用dispatch_group。在 dispatch_group_notify 中，请求main queue 隐藏加载器。