coreData第三方库 MagicalRecord

-(void)buttonClick:(id)sender
{
    UIButton * button = (UIButton *)sender;
    switch (button.tag) {
        case 1:
        {
            //增
            //<1>创建对象
            Student * stu = [Student MR_createEntity];
            //<2>对对象的成员属性进行赋值
            stu.firstName = @"lele";
            stu.lastName = @"du";
            stu.age = @"25";
            //<3>将对象添加到数据库中
            //MR_defaultContext创建上下文对象
            //MR_saveOnlySelfAndWait将修改的结果重新写入数据库
            [[NSManagedObjectContext MR_defaultContext] MR_saveOnlySelfAndWait];
            
        }
            break;
        case 2:
        {
            //删
            Student * stu = [Student MR_findFirst];
            if (stu) {
            [stu MR_deleteEntity];//从内存中删除对象
            }
            //从数据库中删除对象
            [[NSManagedObjectContext MR_defaultContext] MR_saveToPersistentStoreAndWait];
    
        }
            break;
        case 3:
        {
            //改
            NSArray * array = [Student MR_findByAttribute:@"age" withValue:@"30"];
            for (Student * str in array) {
                str.lastName = @"hello";
                str.firstName = @"china";
                str.age = @"lele";
            }
            [[NSManagedObjectContext MR_defaultContext] MR_saveToPersistentStoreAndWait];
            
        }
            break;
        default:
        {
            //查
            //<1>按照条件查询
            NSArray * array = [Student MR_findByAttribute:@"age" withValue:@"25"];
            for (Student * str in array) {
                NSLog(@"%@",str.lastName);
            }
           
            //<2>查询数据库中所有数据信息
            NSArray * array1 = [Student MR_findAll];
            for (Student * str in array1) {
                NSLog(@"%@",str.lastName);
            }
            //<3>查询数据库中第一个数据信息
            Student * stu = [Student MR_findFirst];
            NSLog(@"%@",stu.firstName);
            
        }
            break;
    }
}