Objective-c CoreData

#import "ViewController.h"

#import "Person.h"//引入须要使用的实体

#import <CoreData/CoreData.h>

@interface ViewController ()

{

    //管理对象上下文

    NSManagedObjectContext *_context;

}

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    

    _context = [self createDBContext];

    

    

//    [self addPersonWithName:@"测试员01" sex:@"男" age:@18];

//    [self addPersonWithName:@"测试员02" sex:@"女" age:@16];

//    [self addPersonWithName:@"测试员03" sex:@"男" age:@28];

    

    NSLog(@"%@", [[self getPersonByName:@"测试员01"] valueForKey : @"sex"]);

//    [self removePerson:@"测试员02"];

    [self modifyPersonWithName:@"测试员03" sex:@"女" age:@100];

    

    // Do any additional setup after loading the view, typically from a nib.

}

#pragma mark 1.建立管理上下文

- (NSManagedObjectContext *)createDBContext

{

    NSManagedObjectContext *context;

    //打开模型文件，参数为nil则打开包中全部模型文件并合并成一个

    NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

    //建立解析器NSPersistentStoreCoordinator

    NSPersistentStoreCoordinator *storeCoordinator = [[NSPersistentStoreCoordinator alloc]initWithManagedObjectModel:model];

    //建立数据库保存路径(文件目录)

    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];

    NSLog(@"%@", path);

    path = [path stringByAppendingPathComponent:@"YC.db"];

    

    //添加SQLite持久存储到解析器

    NSError *error;

    [storeCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:[NSURL fileURLWithPath:path] options:nil error:&error];

    if (error) {

        NSLog(@"数据库打开失败！错误: %@", error.localizedDescription);

    }

    else//数据库建立成功（打开成功）

    {

        context = [[NSManagedObjectContext alloc]initWithConcurrencyType:NSMainQueueConcurrencyType];

        context.persistentStoreCoordinator = storeCoordinator;

        NSLog(@"数据库打开成功！");

    }

    

    return context;

}

#pragma mark 2.插入数据

- (void)addPersonWithName : (NSString *)name sex : (NSString *)sex age : (NSNumber *)age

{

    //建立实体对象

    Person *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:_context];

    person.name = name;

    person.sex = sex;

    person.age = age;

    //保存上下文

    NSError *error;

    [_context save:&error];

    if (error) {

        NSLog(@"添加过程当中发送错误，错误: %@", error.localizedDescription);

    }

    else

    {

        NSLog(@"添加成功");

    }

}

#pragma mark 3.查询数据

//NSPredicate(谓词)是一个Foundation的类，它指定数据被获取或者过滤的方式。它的语言就像SQL的where和正则表达式的交叉同样。提供了具备表现力的，天然语言界面来定义一个集合。（被搜索的逻辑条件）

//*zo*    z, zo, zoo, zooo....

//zo+    zo, zoo, zooo, zoooo...

- (NSArray *)getPersonByName : (NSString *)name

{

    //建立一个请求

    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];

    request.predicate = [NSPredicate predicateWithFormat:@"%K=%@",@"name", name];

    //上下文执行请求,获得查询结果

    NSArray *array = [_context executeFetchRequest:request error:nil];

    return array;

}

#pragma mark 4.删除数据

- (void)removePerson : (NSString *)name

{

    Person *person = [[self getPersonByName:name] firstObject];

    [_context deleteObject:person];

    NSError *error;

    [_context save:&error];

    if (error) {

        NSLog(@"删除过程当中发生错误：%@", error.localizedDescription);

    }

    else

    {

        NSLog(@"删除成功");

    }

}

#pragma mark 修改数据

//必须首先提取出对应的实体对象，而后经过修改对象属性，最后保存

- (void)modifyPersonWithName : (NSString *)name sex : (NSString *)sex age : (NSNumber *)age{

    Person *person = [[self getPersonByName:name] firstObject];

    person.sex = sex;

    person.age = age;

    NSError *error;

    [_context save:&error];

    if (error) {

        NSLog(@"修改过程当中发生错误: %@", error.localizedDescription);

    }

    else

    {

        NSLog(@"修改为功");

    }

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end