24_Core Data Demo

今天开始学习Core Data，类似于数据库，可以永久保存数据。不过当把App从iPhone删掉之后就没有了。可以用来保存App的运行数据。

参考链接：iOS Swift教程 Core Data 概述

Part1:

//
//  ViewController.swift
//  Core Data Demo
//
//  Created by zcdll on 16/1/22.
//  Copyright © 2016年 ZC. All rights reserved.
//

import UIKit
import CoreData

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let appDel: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

        let context: NSManagedObjectContext = appDel.managedObjectContext

        //第一次添加时使用，不注释会每次添加一次
        /*
        let newUser = NSEntityDescription.insertNewObjectForEntityForName("Users", inManagedObjectContext: context)

        newUser.setValue("zcdll", forKey: "username")

        newUser.setValue("asdf", forKey: "password")

        do {

            try context.save()

        } catch {

            print("Save problem")

        }
        */

        let request = NSFetchRequest(entityName: "Users")

        do {

            let results = try context.executeFetchRequest(request)

            if results.count > 0 {

                for result in results as! [NSManagedObject] {

                    print(result.valueForKey("username")!)

                    print(result.valueForKey("password")!)

                }

            }

        } catch {

            print("Fetch failed")

        }
    }

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

工程：24_Core_Data_Demo

Part2:

增加了更新数据，删除数据，查询数据等功能，感觉这样写很不灵活。

//
//  ViewController.swift
//  Core Data Demo
//
//  Created by zcdll on 16/1/22.
//  Copyright © 2016年 ZC. All rights reserved.
//

import UIKit
import CoreData

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let appDel: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

        let context: NSManagedObjectContext = appDel.managedObjectContext

        //第一次添加时使用，不注释会每次添加一次
        /*
        let newUser = NSEntityDescription.insertNewObjectForEntityForName("Users", inManagedObjectContext: context)

        newUser.setValue("zcdll12", forKey: "username")

        newUser.setValue("asdf12", forKey: "password")

        do {

            try context.save()

        } catch {

            print("Save problem")

        }
        */

        let request = NSFetchRequest(entityName: "Users")

        //request.predicate = NSPredicate(format: "username = %@", "zcdll3")

        request.returnsObjectsAsFaults = false

        do {

            let results = try context.executeFetchRequest(request)

            if results.count > 0 {

                for result in results as! [NSManagedObject] {

                    /*

                    context.deleteObject(result)
                    //result.setValue("zcdll3",forKey: "username")

                    do {

                        try context.save()

                    } catch {}

                    */

                    if let username = result.valueForKey("username") as? String {

                        print(username)

                    }

                    //print(result.valueForKey("password")!)

                }

            }

        } catch {

            print("Fetch failed")

        }
    }

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

工程：24_Core_Data_Demo