创建Core Data Stack

主要一下几个步骤：

NSManagedObjectModel

NSPresistentStore

NSPersistentStoreCoordinator

NSManagedObjectContext
在这里就不多说每一个都是什么了，可以参考上边给出的两篇博客

Show your code

import CoreDataclass CoreDadaStack {   /// model Name   private let modelName = "Dog Walk"   /// Document Directory URL   private lazy var applicationDocumentsDirectory: NSURL = {       let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)       return urls[urls.count - 1]   }()      /// Managed Object Model   private lazy var managedObjectModel: NSManagedObjectModel = {       let modelURL = NSBundle.mainBundle().URLForResource(self.modelName, withExtension: "momd")       return NSManagedObjectModel(contentsOfURL: modelURL!)!   }()   /// Presistent Store Coordinator   private lazy var psc: NSPersistentStoreCoordinator = {       let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)       let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent(self.modelName)       do {           let options = [NSMigratePersistentStoresAutomaticallyOption:true]           try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: options)       }catch {           print("添加持久化存储区错误")       }       return coordinator   }()   /// Managed Object Context   lazy var context: NSManagedObjectContext = {       var managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)       managedObjectContext.persistentStoreCoordinator = self.psc       return managedObjectContext   }()   /**    Save Context Data    */   func saveContext() {       if context.hasChanges {           do {               try context.save()           } catch let error as NSError {               print("错误 ❌ \(error.localizedDescription)")               abort()           }       }   }}

选择ViewController.swift添加下边代码

import CoreData

添加属性：

var managedContext: NSManagedObjectContext!

然后打开AppDelegate.swift

import CoreData

添加属性：

lazy var coreDataStack = CoreDataStack()

在application(_:didFinishLaunchingWithOptions:)添加下边代码

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {        let navigationController = window?.rootViewController as! UINavigationController    let viewcontroller = navigationController.topViewController as! ViewController    viewcontroller.managedContext = coreDataStack.context    return true  }

最后我们在 UIApplicationDelegate的两个方法中调用存储方法

func applicationWillTerminate(application: UIApplication) {        coreDataStack.saveContext()    }    func applicationDidEnterBackground(application: UIApplication) {        coreDataStack.saveContext()    }

Modeling your data

打开Dog Walk

添加 Dog Entity ,添加属性 name 类型为 String

添加 Walk Entity, 添加属性 date 类型为 Date

接下来我们完成关系。

打开 Dog Entity ,添加relationship name 为 walks Set the destination to Walk

在属性版中修改Type类型，To Many ,勾选 Ordered

打开 Walk Entity , 添加relationship name 为 dog relationship 为 Dog Set the destination as dog and the inverse as walks.

Adding managed object subclasses

command + n 选择 NSManagedObject Subclass 选择 Dog Walk model 并且选中 Dog 和 Walk entities。语言选择 Swift

我在生成的Walk.swift和 Dog.swift中都重写了父类的方法，为了在生成这两个类的时候有代码提示。

override init(entity: NSEntityDescription, insertIntoManagedObjectContext context: NSManagedObjectContext?) {        super.init(entity: entity, insertIntoManagedObjectContext: context)    }

A walk down persistence lane

如果你上边的步骤都已经完成了，那么我们就可以开始存储数据了。

首先在ViewController.swift中添加一个属性 var currentDog: Dog! 然后我们在viewDidLoad()中来添加一些数据

//创建一个 Entitylet dogEntity = NSEntityDescription.entityForName("Dog", inManagedObjectContext: managedContext)   let dogName = "Fido"   //首先来检查在数据库中是否存在一个名为 Fido  的狗过       let dogFetch = NSFetchRequest(entityName: "Dog")   dogFetch.predicate = NSPredicate(format: "name == %@", dogName)   do{   //执行查询       let results = try managedContext.executeFetchRequest(dogFetch) as! [Dog]       //如果这个狗狗存在的话直接获取赋值给 currentDog       if results.count > 0 {           currentDog = results.first       }else {       //如果不存在 则实例化一个Dog           currentDog = Dog(entity: dogEntity!, insertIntoManagedObjectContext: managedContext)           currentDog.name = dogName           try managedContext.save()       }   }catch let error as NSError{       print("Error:\(error)" + "description:\(error.localizedDescription)")   }

接下来我们来实现点击添加按钮之后添加新狗狗散步时间的功能。

@IBAction func add(sender: AnyObject) {   //添加一个新的 Walk Entity into Core Data    let walkEntity = NSEntityDescription.entityForName("Walk", inManagedObjectContext: managedContext)   let walk = Walk(entity: walkEntity!, insertIntoManagedObjectContext: managedContext)   walk.date = NSDate.timeIntervalSinceReferenceDate()      //insert the new walk into the dog's walks set   let walks = currentDog.walks!.mutableCopy() as! NSMutableOrderedSet   walks.addObject(walk)   currentDog.walks = walks.copy() as? NSOrderedSet   //save the managed object context   do {       try managedContext.save()   }catch let error as NSError {       print("Could not save:\(error)")   }      tableView.reloadData() }

现在你运行程序，点击➕就可以看到有新的数据在列表中显示。

Deleting objects from Core Data

我们接下来就是要把我们添加的数据删除。

我们来重写下边的方法

func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {        if editingStyle == .Delete {           //选择要删除的walk           let walkToRemove = currentDog.walks![indexPath.row] as! Walk           //删除           managedContext.deleteObject(walkToRemove)           do {               //保存操作               try managedContext.save()           }catch let error as NSError {               print("Could not save: \(error)")           }           // 删除视图中的数据           tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Automatic)       } }

运行你的app 来试试吧。