コアデータのManagedObjectContext.ExecuteFetchRequestを非同期で非同期にする方法

Question

以下は私のコードです。

私に問題を与えている行はlet fetchRequest = try moc.executeFetchRequest(fetchRequest) as! [AppSettings]が非同期に読み込まれているように見えますが、それを同期的にロードして、ユーザー名レコードが正しくチェックされるようにします。

どうすればよいですか？

私はプログラムをいつでも起動して停止すると、エンティティが時間の約80％、ランダムに20％の時間が見つからないため、非同期で読み込まれることが分かります。 （私は常に、プログラムを起動し、停止していますので）他に何も実体を変えていないので、それはコードが、私は、コマンド

guard let appSettingsArrayItem = fetchRequest.first where fetchRequest.count>0 else { 
       print ("no entities found...") 
       return false 
      } 

を使用するときにそれはいずれかを見つけることができないasynchrnously実行されているという意味になるだろう時々エンティティ。チェックログイン機能

import UIKit 
import CoreData 

class LoginViewController: UIViewController, UITextFieldDelegate { 

    @IBOutlet weak var usernameField: UITextField! 
    @IBOutlet weak var passwordField: UITextField! 

    var isLoggedIn = false 

    let moc = DataController().managedObjectContext 

    @IBAction func SignUpButtonPressed(sender: UIButton) { 
     print("sign up") 
    } 

    func textFieldShouldReturn(textField: UITextField) -> Bool { 
     textField.resignFirstResponder() 
     return true 
    } 

    func textFieldShouldEndEditing(textField: UITextField) -> Bool { 
     textField.resignFirstResponder() 
     return true 
    } 


    override func viewDidLoad() { 
     super.viewDidLoad() 

     let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "dismissKeyboard") 
     view.addGestureRecognizer(tap) 

     print("view loaded, check if already signed in here") 

     let loggedIn = checkIfLoggedInAlready() //checks database to see 

     if(loggedIn){ 
      print("was logged in!") 
      isLoggedIn = true 

      self.performSegueWithIdentifier("loginSegue", sender: self) 
     } 
    } 

    func checkIfLoggedInAlready() -> Bool{ 
     let fetchRequest = NSFetchRequest(entityName: "AppSettings") 
     //let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest) //Deletes ALL appsettings entities 

     do { 

      let fetchRequest = try moc.executeFetchRequest(fetchRequest) as! [AppSettings] 

      guard let appSettingsArrayItem = fetchRequest.first where fetchRequest.count>0 else { 
       print ("no entities found...") 
       return false 
      } 

      guard let username = (appSettingsArrayItem as AppSettings).username else{ 
       print ("username not found") 
       return false 
      } 

      print("number Of AppSetting Entities =\(fetchRequest.count)") 
      print(username) 

      //The following code deletes ALL the entities! 
      //try moc.persistentStoreCoordinator!.executeRequest(deleteRequest, withContext: moc) 

      //To delete just '1' entry use the code below. 

      //moc.deleteObject(appSettingsArrayItem) 
      //try moc.save()//save deletion change. 

      //print("deleted particular entity item") 

      return true 
     } catch{ 
      fatalError("bad things happened \(error)") 
     } 


    } 

    func dismissKeyboard() { 
     //Causes the view (or one of its embedded text fields) to resign the first responder status. 
     view.endEditing(true) 
    } 

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

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { 
     // Get the new view controller using segue.destinationViewController. 
     // Pass the selected object to the new view controller. 
     print("prepare seque") 
    } 

    func displayErrorMessage(errorMessage: String){ 
     print("show error console with Error:"+errorMessage) 
     let alert = UIAlertController(title: "Error", message: errorMessage, preferredStyle: UIAlertControllerStyle.Alert) 
     alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil)) 
     self.presentViewController(alert, animated: true, completion: nil) 
    } 

    override func shouldPerformSegueWithIdentifier(identifier: String, sender: AnyObject?) -> Bool { 
     switch(identifier){ 
      case "loginSegue": 
       print("Is the user already logged in?") 
       if(isLoggedIn){ 
        print("Detected as YES") 
        return true 
       } 
       print("Detected as NO, so checking username and password fields next...") 

       guard let password = passwordField.text!.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet()) where !password.isEmpty else { 
        displayErrorMessage("Password can not be empty!") 
        return false 
       } 

       guard let username = usernameField.text!.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet()) where !username.isEmpty else{ 
        displayErrorMessage("Username can not be empty!") 
        return false 
       } 

       let url = "http://distribution.tech/restapi/v1/userlogin?email="+username+"&password="+password 
       print(url) 

       let json = JSON(url:url) 
       print(json) 

       if(json["status"].asInt==1){ 

        let entity = NSEntityDescription.insertNewObjectForEntityForName("AppSettings", inManagedObjectContext: moc) as! AppSettings 

        entity.setValue(username, forKey: "username") 
        entity.setValue(password, forKey: "password") 
        entity.setValue(json["tokenid"].asString, forKey: "token") 
        entity.setValue(json["roleid"].asInt, forKey: "roleid") 
        entity.setValue(json["role"].asString, forKey: "role") 
        entity.setValue(json["companyid"].asInt , forKey: "companyid") 
        entity.setValue(json["isdev"].asInt, forKey: "isdev") 

        //save token and other details to database. 
        do { 
         try moc.save() 
         print("saved to entity") 
        }catch{ 
         fatalError("Failure to save context: \(error)") 
        } 

//     token 
//     roleid int 
//     role 
//     companyid int 
//      
//     { 
//      "companyid": 3, 
//      "userid": 2, 
//      "tokenid": "804febae26ddbd0292b3d2c66b30afd5028d5ba9", 
//      "status": 1, 
//      "roleId": 1, 
//      "role": "super_admin", 
//      "isdev": 0 
//     } 

        //Save to disk using our own method, as COREDATA is unreliable! 

        return true //login succesfull 
       }else{ 
        displayErrorMessage("Incorrect Username or Email") 
        return false//failed 
       } 

     default: 
      displayErrorMessage("Unknown Error Related To Segue Not Found") 
     } 
     return false //if it gets to this point assume false 
    } 


} 

管理対象オブジェクトは、そのファイルは以下ここでDataControllerで作成されたを含む

チェックログイン機能

func checkIfLoggedInAlready() -> Bool{ 
     let fetchRequest = NSFetchRequest(entityName: "AppSettings") 
     //let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest) //Deletes ALL appsettings entities 

     do { 

      let fetchRequest = try moc.executeFetchRequest(fetchRequest) as! [AppSettings] 

      guard let appSettingsArrayItem = fetchRequest.first where fetchRequest.count>0 else { 
       print ("no entities found...") 
       return false 
      } 

      guard let username = (appSettingsArrayItem as AppSettings).username else{ 
       print ("username not found") 
       return false 
      } 

      print("number Of AppSetting Entities =\(fetchRequest.count)") 
      print(username) 

      //The following code deletes ALL the entities! 
      //try moc.persistentStoreCoordinator!.executeRequest(deleteRequest, withContext: moc) 

      //To delete just '1' entry use the code below. 

      //moc.deleteObject(appSettingsArrayItem) 
      //try moc.save()//save deletion change. 

      //print("deleted particular entity item") 

      return true 
     } catch{ 
      fatalError("bad things happened \(error)") 
     } 


    } 

全体LoginViewController。それは時間のエンティティのほとんどを検索していた場合、エンティティ&コンソール時には

イメージ参照を発生することがありますエンティティ&コンソールエラーの

import UIKit 
import CoreData 

class DataController: NSObject { 
    var managedObjectContext: NSManagedObjectContext 
    override init() { 
     // This resource is the same name as your xcdatamodeld contained in your project. 
     guard let modelURL = NSBundle.mainBundle().URLForResource("AppSettings", withExtension:"momd") else { 
      fatalError("Error loading model from bundle") 
     } 
     // The managed object model for the application. It is a fatal error for the application not to be able to find and load its model. 
     guard let mom = NSManagedObjectModel(contentsOfURL: modelURL) else { 
      fatalError("Error initializing mom from: \(modelURL)") 
     } 
     let psc = NSPersistentStoreCoordinator(managedObjectModel: mom) 
     self.managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType) 
     self.managedObjectContext.persistentStoreCoordinator = psc 
     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0)) { 
      let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask) 
      let docURL = urls[urls.endIndex-1] 
      /* The directory the application uses to store the Core Data store file. 
      This code uses a file named "DataModel.sqlite" in the application's documents directory. 
      */ 
      let storeURL = docURL.URLByAppendingPathComponent("AppSettings.sqlite") 
      do { 
       try psc.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: storeURL, options: nil) 
      } catch { 
       fatalError("Error migrating store: \(error)") 
      } 
     } 
    } 
} 

イメージ参照