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:9999 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