swift 3 Xcode 8 中的 NSManagedObject 和 CoreData

Posted 2023-02-24

【中文标题】swift 3 Xcode 8 中的 NSManagedObject 和 CoreData

【英文标题】：NSManagedObject and CoreData in swift 3 Xcode 8

【发布时间】：2016-11-01 08:00:32

【问题描述】：

我正在使用 Xcode 8 和 swift 3，我正在从编辑器菜单 NSManageObjectModel 为我的实体创建 NSManagedObject，如何使用此文件来获取和创建对象，在 Xcode 7 中我正在使用核心数据堆栈来创建管理对象、持久存储和 ,....现在我不知道如何在swift 3中使用核心数据。

【参考方案1】：

swift 3 中的以下核心数据代码使用 x 代码 8 及更高版本工作正常，部署目标可以是低 ios 8 及更高版本，一旦尝试即可工作。我逐步编写代码。

1)在appdelegate中导入Coredata

          import UIKit
          import CoreData


        @UIApplicationMain
    class AppDelegate: UIResponder, UIApplicationDelegate 
              var window: UIWindow?

在 appdelegate 中添加的这段代码中，只有当 coredata 在所有版本的操作系统中工作时，你才需要这段代码

private lazy var applicationDocumentsDirectory: URL = 
  let urls = FileManager.default.urls(for: .documentDirectory, in:
                                  .userDomainMask)

 return urls[urls.count-1]
 ()
 //   Core Data stack


lazy var managedObjectModel: NSManagedObjectModel = 
let modelURL = Bundle.main.url(forResource: "Coredata", withExtension: "momd")!
return NSManagedObjectModel(contentsOf: modelURL)!
()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = 
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.appendingPathComponent("SingleViewCoreData.sqlite")
var failureReason = "There was an error creating or loading the application's saved data."
do 
    try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
 catch 
    var dict = [String: AnyObject]()
    dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
    dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?
    dict[NSUnderlyingErrorKey] = error as NSError
    let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
    NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
    abort()
  
   return coordinator
   ()

  lazy var managedObjectContext: NSManagedObjectContext = 
  let coordinator = self.persistentStoreCoordinator
  var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
  managedObjectContext.persistentStoreCoordinator = coordinator
  return managedObjectContext
  ()
 //   Core Data Saving support
     func saveContext () 
     if managedObjectContext.hasChanges 
    do 
        try managedObjectContext.save()
     catch 
        let nserror = error as NSError
        NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
        abort()
     
    
   

3.保存数据这是你需要的数据保存到数据库然后 你写下面的代码 这个在 ViewControllers 类中的写入只是再次导入 coredata 并创建 NSManagedObject

      var dataBase = [NSManagedObject]()


    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let managedContext = appDelegate.managedObjectContext
    let entity =  NSEntityDescription.entity(forEntityName:

   "YourEntityName",in:managedContext)
    let activityData = NSManagedObject(entity: entity!,insertInto:
    managedContext)
    activityData.setValue(storeData1, forKey: "attributeKey1")
    activityData.setValue(storeData2, forKey: "attributeKey2")

    do 
        try managedContext.save()
        dataBase.append(activityData)


     catch let error as NSError  
        print("Could not save \(error), \(error.userInfo)")
    

4.你在哪个类中获取数据然后你写这段代码这里也一样 就是这样

import coredata and create NSMangedObject

   var getData= [NSManagedObject]()

//获取数据 func getLogsData()

let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "YourEntityName")

do 
    let results = try managedContext.fetch(fetchRequest)

      catch let error as NSError 
    print("Could not fetch \(error), \(error.userInfo)")