ios中coredata

http://blog.csdn.net/q199109106q/article/details/8563438

//
//  MJViewController.m
//  数据存储5-Core Data
//
//  Created by mj on 13-4-16.
//  Copyright (c) 2013年 itcast. All rights reserved.
//

#import "MJViewController.h"
#import <CoreData/CoreData.h>
#import "NSString+File.h"
#import "Person.h"

@interface MJViewController ()
@property (nonatomic, retain) NSManagedObjectContext *context;
@end

@implementation MJViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 初始化上下文对象
    [self initContext];

    // 插入数据
    //[self addData];
    //[self addPerson];

    // 删除数据
    //[self deleteData];

    // 查询数据
    [self findPerson];

    //  更改数据
    //[self updateData];
}

- (void)dealloc {
    [_context release];
    [super dealloc];
}

#pragma mark 查询数据
- (void)findPerson {
    // 初始化查询对象
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];

    NSArray *array = [self.context executeFetchRequest:request error:nil];

    for (Person *person in array) {
        NSLog(@"name=%@,age=%@", person.name, person.age);
    }
}

#pragma mark 插入数据
- (void)addPerson {
    // 初始化一个跟上下文关联的对象
    Person *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:self.context];

    person.name = @"mj";
    person.age = [NSNumber numberWithInt:];

    [self.context save:nil];
}

#pragma mark 删除数据
- (void)deleteData {
    // 初始化查询对象
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];

    // 设置条件过滤 where age < 50
    request.predicate = [NSPredicate predicateWithFormat:@"age < %i", ];

    NSArray *array = [self.context executeFetchRequest:request error:nil];

    for (NSManagedObject *person in array) {
        // 删除掉的person对象就不会跟context关联了
        [self.context deleteObject:person];
    }

    // 将所有跟上下文相关联的对象同步到数据库
    [self.context save:nil];
}

#pragma mark 查询数据
- (void)updateData {
    // 初始化查询对象
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];

    // 设置条件过滤 where age > 20
    request.predicate = [NSPredicate predicateWithFormat:@"age > %i", ];

    NSArray *array = [self.context executeFetchRequest:request error:nil];

    for (NSManagedObject *person in array) {
        [person setValue:[NSNumber numberWithInt:] forKey:@"age"];
    }

    // 将所有跟上下文相关联的对象同步到数据库
    [self.context save:nil];
}

#pragma mark 查询数据
- (void)findData {

    // 初始化查询对象
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];

    // 按照age降序
    NSSortDescriptor *desc = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:NO];

    request.sortDescriptors = [NSArray arrayWithObject:desc];

    // 设置条件过滤 where age > 20
    //request.predicate = [NSPredicate predicateWithFormat:@"age > %i", 20];

    // name like '%j-1%'
    //request.predicate = [NSPredicate predicateWithFormat:@"name like %@", @"*j-1*"];

    NSArray *array = [self.context executeFetchRequest:request error:nil];

    for (NSManagedObject *person in array) {
        NSString *name = [person valueForKey:@"name"];

        int age = [[person valueForKey:@"age"] intValue];

        NSLog(@"name=%@,age=%i", name, age);
    }

}

#pragma mark 插入数据
- (void)addData {
    //[[NSManagedObject alloc] initWithEntity:<#(NSEntityDescription *)#> insertIntoManagedObjectContext:<#(NSManagedObjectContext *)#>];

    for (int i = ; i<; i++) {
        // 初始化一个跟上下文关联的对象
        NSManagedObject *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:self.context];

        // 设置对象的属性
        [person setValue:[NSNumber numberWithInt:+i] forKey:@"age"];
        NSString *name = [NSString stringWithFormat:@"mj-%i", i];
        [person setValue:name forKey:@"name"];
    }

    // 将所有跟上下文相关联的对象同步到数据库
    [self.context save:nil];
}

#pragma mark 初始化上下文对象
- (void)initContext {
    // 1.加载模型文件
    // nil代表从应用程序主bundle里面加载模型文件
    NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil] ;

    // 2.初始化持久化存储调度器
    NSPersistentStoreCoordinator *store = [[[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model] autorelease];

    // 添加持久化存储库（这里用数据库存储）
    NSString *path = [@"coredata.db" documentsAppend];

    NSURL *url = [NSURL fileURLWithPath:path];

    // 一定要给指针赋值
    NSError *error = nil;
    [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:&error];

    if (error) {
        NSLog(@"打开数据库失败:%@", [error localizedDescription]);
        return;
    }

    // 3.初始化上下文对象
    self.context = [[[NSManagedObjectContext alloc] init] autorelease];
    self.context.persistentStoreCoordinator = store;
}

@end

下面是面向模型

#import "ViewController.h"
#import <CoreData/CoreData.h>
#import "Person.h"
#import "Car.h"
@interface ViewController ()

@property(nonatomic,retain)NSManagedObjectContext *context;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    //从应用程序加载模型文件
    NSManagedObjectModel *model=[NSManagedObjectModel mergedModelFromBundles:nil];
    //传入模型对象，初始化NSPersistentStoreCoordinator对象
    NSPersistentStoreCoordinator *psc=[[[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model] autorelease];
    //构建sqlite数据库文件的路径
    NSString *docs=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

    NSURL *url=[NSURL fileURLWithPath:[docs stringByAppendingPathComponent:@"person.db"]];
    NSError *error=nil;

    if (![psc addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:&error]) {

        //[NSException raise:@"创建数据库失败" format:@"%@",[error localizedDescription]];
        NSLog(@"创建数据库失败-->%@",[error localizedDescription]);
    }

    self.context=[[NSManagedObjectContext alloc] init];
    self.context.persistentStoreCoordinator=psc;
    [_context release];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)addclick:(id)sender {
    Person *person=[NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:self.context];
    person.name=@"gcb111";
    person.age=@;

    Car *car=[NSEntityDescription insertNewObjectForEntityForName:@"Car" inManagedObjectContext:self.context];
    //[car setValue:@"123456789456" forKey:@"no"];
    car.no=@"ssss111111";

    car.person=person;

    NSError *error=nil;
    [self.context save:&error];
    if(error){
        NSLog(@"-->同步失败-->%@",error.localizedDescription);
    }
    else{
        NSLog(@"--->同步成功-->");
    }
}

- (IBAction)selectClick:(id)sender {

    //创建查询请求
    NSFetchRequest *request=[[NSFetchRequest alloc] init];
    //获取请求的实体
    request.entity=[NSEntityDescription entityForName:@"Person" inManagedObjectContext:self.context];
    NSSortDescriptor *sort=[[NSSortDescriptor alloc] initWithKey:@"age" ascending:YES];
    request.sortDescriptors=@[sort];
    NSError *error=nil;
    NSArray *arr=[self.context executeFetchRequest:request error:&error];
    if (error) {
        NSLog(@"-->查询失败-%@",error.localizedDescription);
        return;
    }
    for (Person *p in arr) {
        NSLog(@"-->%@-->%@",p.name,p.age);
    }    

}

- (IBAction)UpdateClick:(id)sender {
    NSArray *arr=[self queryByAge:];
    for (Person *p in arr) {
        p.age=@;
    }
    NSError *error=nil;
    [self.context save:&error];
    if (error) {
        NSLog(@"-->失败-%@",error);

    }
}

- (IBAction)DelClick:(id)sender {

    NSArray *arr=[self queryByAge:];
    for (Person *p in arr) {
        [self.context deleteObject:p];
    }
    NSError *error=nil;
    [self.context save:&error];
    if (error) {
        NSLog(@"-->失败-%@",error);

    }
}

-(NSArray *)queryByAge:(int)age{
    NSFetchRequest *request=[[NSFetchRequest alloc] init];
    request.entity=[NSEntityDescription entityForName:@"Person" inManagedObjectContext:self.context];

    NSPredicate *predicate=[NSPredicate predicateWithFormat:@"age=%i",age];
    request.predicate=predicate;
    NSError *error=nil;
    NSArray *arr=[self.context executeFetchRequest:request error:&error];
    if (error) {
        NSLog(@"-->查询失败-%@",error.localizedDescription);
        return nil;
    }
    return  arr;
}