coredata

coreData开发

1.新建数据模型文件*.xcdatamodeld

2.在数据模型文件中创建实体并创建实体间的关系

3.新建NSManagedObject对象，根据实体定义，生成模型对象

 

4.NSManagedObjectContext 负责应用与数据库间的交互(CRUD)

5.NSPersistentStoreCoordinator 添加持久化数据库（如SQL的数据库），是物理数据存储的物理文件和程序间联系的桥梁，负责管理不同对象上下文

#import "ViewController.h"
#import <CoreData/CoreData.h>

#import "Person.h"
#import "Book.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *bgImageView;
@property(nonatomic,retain)NSManagedObjectContext *context;
@end

@implementation ViewController

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

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


//1.打开数据库
-(void)openDB{
    //1.实例化NSManagedObjectModel数据模型，将所有的模型都加载进来(merged合并)
    NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];//从bundles文件中将所有NSManagedObjectModel合并后，得到最终的数据模型
    //2.实例化数据存储的桥梁!!!!!!!!!!!!!
    NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc]initWithManagedObjectModel:model];
    //3.添加调度,打开或创建数据库
    NSError *error = nil;
    NSArray *docs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [docs[0] stringByAppendingPathComponent:@"my.db"];
    NSURL *url = [NSURL fileURLWithPath:path];
   [store addPersistentStoreWithType:NSSQLiteStoreType
                       configuration:nil
                                 URL:url//本地db的地址
                             options:nil
                               error:&error];
    if(error){
        NSLog(@"打开数据出错:error=%@",error);
        return;
    }
    //4.创建上下文
    _context  = [[NSManagedObjectContext alloc]init];
    _context.persistentStoreCoordinator = store;//添加对应的桥梁
    
}

//2.新增个人记录
-(void)addPerson{
    //1.实例化一条个人记录,通过NSEntityDescription实例描述添加一个实例
    Person *p = [NSEntityDescription insertNewObjectForEntityForName:@"Person"
                                              inManagedObjectContext:_context];
    
    p.name = @"刘德华";
    p.age  = @(19);
    p.phoneNum = @"10086";
    p.image = UIImageJPEGRepresentation([UIImage imageNamed:@"detail.jpg"], 0.1);//添加NSData数据
    //新增书
    Book *b = [NSEntityDescription insertNewObjectForEntityForName:@"Book" inManagedObjectContext:_context];
    b.name = @"奋斗好地方";
    b.price = @(0.64);
    
    Book *b2 = [NSEntityDescription insertNewObjectForEntityForName:@"Book" inManagedObjectContext:_context];
    b2.name = @"乔布斯传";
    b2.price = @(4.6);
    NSSet *bookSet = [NSSet setWithObjects:b,b2,nil];
    p.books = bookSet;//对多关系
    
    NSError *error = nil;
    [_context save:&error];//一次保存所有记录
}

//3.查询所有用户记录
-(void)allPersons{
    //1.实例化一个查询请求
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
    //2.条件查询
//    request.predicate =  [NSPredicate predicateWithFormat:@"age < 60 && name LIKE '*华'"];
//    request.predicate = [NSPredicate predicateWithFormat:@"%K CONTAINS '华' ",@"name"];//通过KeyPath此处不能用%@，得用%K
//    request.predicate =  [NSPredicate predicateWithFormat:@"ANY books.name CONTAINS '时代'"];//多表查询
    NSError *error = nil;
    NSArray *personArray = [_context executeFetchRequest:request error:&error];
    for (Person *p in personArray) {
        NSLog(@"personName=%@ personAge=%@ personPhone=%@",p.name,p.age,p.phoneNum);
        for (Book *b in p.books) {
            NSLog(@"bookName=%@ bookPrice=%@",b.name,b.price);
        }
        self.bgImageView.image = [UIImage imageWithData:p.image];
    }
}
@end

结果：

2015-02-20 17:08:01.995 CoredataDemo[2549:90078] personName=张学友 personAge=29 personPhone=10010
2015-02-20 17:08:01.998 CoredataDemo[2549:90078] bookName=剩女时代 bookPrice=0.64
2015-02-20 17:08:01.998 CoredataDemo[2549:90078] bookName=夜空最亮的星 bookPrice=4.6
2015-02-20 17:08:02.001 CoredataDemo[2549:90078] personName=刘德华 personAge=19 personPhone=10086
2015-02-20 17:08:02.001 CoredataDemo[2549:90078] bookName=乔布斯传 bookPrice=4.6
2015-02-20 17:08:02.001 CoredataDemo[2549:90078] bookName=奋斗好地方 bookPrice=0.64