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。
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.
}
}
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.
}
}
