CoreData的增删改查

首先使用CoreData创建Demo，勾上CoreData选项

然后创建Entity对象，点击Add Entity（+）按钮

生成Entity对象

重命名双击Entity选项，然后输入Person

设置Person属性，点击Attributes选项中的+号，实现添加属性，并给属性命名，且添加属性相关的类型

然后command+N，创建NSManagedObject subclass

然后点击Next

然后勾上 CoreData_Demo选项，然再点击Next

接着勾上Person选项，再次点击Next

接下来，跟着系统的提示进行操作，最后生成Person类

下面是相关操作的代码

AppDelegate.h头文件的代码

 #import <UIKit/UIKit.h>
 #import <CoreData/CoreData.h>

 @interface AppDelegate : UIResponder <UIApplicationDelegate>

 @property (strong, nonatomic) UIWindow *window;

 @property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
 @property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
 @property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;

 - (void)saveContext;
 - (NSURL *)applicationDocumentsDirectory;

 @end

AppDelegate.h实现文件的代码

 #import "AppDelegate.h"
 #import "RootViewController.h"
 @interface AppDelegate ()

 @end

 @implementation AppDelegate

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
     // Override point for customization after application launch.
     self.window.backgroundColor = [UIColor whiteColor];

     self.window.rootViewController = [[RootViewController alloc] init];

     [self.window makeKeyAndVisible];
     return YES;
 }

 - (void)applicationWillTerminate:(UIApplication *)application {
     // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
     // Saves changes in the application's managed object context before the application terminates.
     [self saveContext];
 }

 #pragma mark - Core Data stack

 @synthesize managedObjectContext = _managedObjectContext;
 @synthesize managedObjectModel = _managedObjectModel;
 @synthesize persistentStoreCoordinator = _persistentStoreCoordinator;

 - (NSURL *)applicationDocumentsDirectory {
     // The directory the application uses to store the Core Data store file. This code uses a directory named "com.YXYC.Test_CoreData_Test" in the application's documents directory.
     return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
 }

 - (NSManagedObjectModel *)managedObjectModel {
     // 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.
     if (_managedObjectModel != nil) {
         return _managedObjectModel;
     }
     NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Test_CoreData_Test" withExtension:@"momd"];
     _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
     return _managedObjectModel;
 }

 - (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
     // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it.
     if (_persistentStoreCoordinator != nil) {
         return _persistentStoreCoordinator;
     }

     // Create the coordinator and store

     _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
     NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Test_CoreData_Test.sqlite"];
     NSError *error = nil;
     NSString *failureReason = @"There was an error creating or loading the application's saved data.";
     if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
         // Report any error we got.
         NSMutableDictionary *dict = [NSMutableDictionary dictionary];
         dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application's saved data";
         dict[NSLocalizedFailureReasonErrorKey] = failureReason;
         dict[NSUnderlyingErrorKey] = error;
         error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code: userInfo:dict];
         // Replace this with code to handle the error appropriately.
         // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
         NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
         abort();
     }

     return _persistentStoreCoordinator;
 }

 - (NSManagedObjectContext *)managedObjectContext {
     // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
     if (_managedObjectContext != nil) {
         return _managedObjectContext;
     }

     NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
     if (!coordinator) {
         return nil;
     }
     _managedObjectContext = [[NSManagedObjectContext alloc] init];
     [_managedObjectContext setPersistentStoreCoordinator:coordinator];
     return _managedObjectContext;
 }

 #pragma mark - Core Data Saving support

 - (void)saveContext {
     NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
     if (managedObjectContext != nil) {
         NSError *error = nil;
         if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
             // Replace this implementation with code to handle the error appropriately.
             // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
             NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
             abort();
         }
     }
 }

 @end

RootViewController.h头文件相关的代码

 #import <UIKit/UIKit.h>

 @interface RootViewController : UIViewController

 @end

RootViewController.h实现文件相关的代码

 #import "RootViewController.h"
 #import "AppDelegate.h"
 @interface RootViewController ()

 @property (strong, nonatomic) AppDelegate *appDelegate;

 @end

 @implementation RootViewController

 - (void)viewDidLoad {
     [super viewDidLoad];
     self.appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
     // 存储数据
     [self saveData];
     // 查询全部数据
     [self readData];
     NSMutableArray *datas = [[NSMutableArray alloc] init];
     // 得到查询的结果（条件查询）
     datas = [self getObjectsWithPredicate];
     // 删除
     [self removeObjects];
     // 修改
     [self changeObjects];
 }

 /**
  *  存储数据
  */
 - (void)saveData
 {
     NSManagedObjectContext *object = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:self.appDelegate.managedObjectContext];
     [object setValue:@"GL" forKey:@"name"];
     [object setValue:@"female" forKey:@"sex"];

 }

 /**
  *  查询全部数据
  */
 - (void)readData
 {
     // 实例化一个查询（Fetch）请求
     NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
     NSEntityDescription *object = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:self.appDelegate.managedObjectContext];
     [fetch setEntity:object];

     NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO];
     NSLog(@"sort:%@",sort);

     NSArray *sortarr = [[NSArray alloc] initWithObjects:sort, nil];
     [fetch setSortDescriptors:sortarr];

     NSError *error = nil;
     // 让_context执行查询数据
     NSArray *fetchresult = [self.appDelegate.managedObjectContext executeFetchRequest:fetch error:&error];

     for (NSManagedObject *object in fetchresult) {
         NSLog(@"name:%@==sex:%@",[object valueForKey:@"name"],[object valueForKey:@"sex"]);
     }

 }
 /**
  *  条件查询
  *
  *  @return 查询结果的Entity数组
  */
 - (NSMutableArray *)getObjectsWithPredicate
 {
     NSError *error = nil;
     // 实例化一个查询（Fetch）请求
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
     // 条件查询
     request.predicate = [NSPredicate predicateWithFormat:@"sex LIKE '*female'"];
     // 让_context执行查询数据
     NSArray *array = [self.appDelegate.managedObjectContext executeFetchRequest:request error:&error];
     return [NSMutableArray arrayWithArray:array];
 }
 /**
  *  删除操作
  */
 - (void)removeObjects
 {
     NSError *error = nil;
     // 实例化查询请求
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
     // 设置条件
     request.predicate = [NSPredicate predicateWithFormat:@"name = 'LF'"];
     // 由上下文查询数据
     NSArray *result =[self.appDelegate.managedObjectContext executeFetchRequest:request error:&error];
     // 打印条件结果,并删除对象
     for (NSManagedObject *object in result) {
         // 删除对象
         [self.appDelegate.managedObjectContext deleteObject:object];
     }
     // 删除后，保存数据
     [self.appDelegate.managedObjectContext save:&error];
 }
 /**
  *  修改
  */
 - (void)changeObjects
 {
     NSError *error = nil;
     // 实例化查询请求
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
     // 设置条件
     request.predicate = [NSPredicate predicateWithFormat:@"name = 'GL'"];
     // 由上下文查询数据
     NSArray *result =[self.appDelegate.managedObjectContext executeFetchRequest:request error:&error];
     // 修改对象
     for (NSManagedObject *object in result) {
         // 修改对象
         [object setValue:@"GYL" forKey:@"name"];
     }
     // 修改后，保存数据
     [self.appDelegate.managedObjectContext save:&error];
 }

 @end