CoreData的简单使用<四、多个数据库>

CoreData的多个数据库

//
//  ViewController.m
//  CoreData
//
//  Created by YanFengZheng on 16/8/27.
//  Copyright © 2016年 fe. All rights reserved.
//

#import "ViewController.h"
#import <CoreData/CoreData.h>
#import "Employee.h"
#import "Friendster.h"
@interface ViewController ()
@property (nonatomic,strong) NSManagedObjectContext *componyContext;
@property (nonatomic,strong) NSManagedObjectContext *weiChartContext;
@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
self.componyContext = [self getContextWithDateModel:@"Compony.momd"];
self.weiChartContext = [self getContextWithDateModel:@"WeiChart.momd"];

}

#pragma mark - 数据库操作 增、删、改、查
//1.插入数据
- (IBAction)insertData:(UIButton *)sender {
//插入数据的时候，需要使用实体描述拿到实体模型
Employee *employee = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.componyContext];
employee.name = @"王五";
employee.height = @190;
employee.birthday = [NSDate date];

[self.componyContext  save:nil];

Friendster *friend = [NSEntityDescription insertNewObjectForEntityForName:@"Friendster" inManagedObjectContext:self.weiChartContext];
friend.text = @"秋天来了，天气凉了";
friend.date = [NSDate date];
[self.weiChartContext  save:nil];
}

//查询员工
- (IBAction)queryData:(UIButton *)sender {
//1:FectchRequest 抓取请求对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
//2:设置过滤条件
NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"王五"];
request.predicate = pre;
//3:设置排序
NSSortDescriptor *height = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
request.sortDescriptors = @[height];

//4:执行请求
NSArray *emps = [self.componyContext executeFetchRequest:request error:nil];
//遍历查询结果
for (Employee *emp in emps) {
NSLog(@"名字：%@,身高：%@,生日：%@",emp.name,emp.height,emp.birthday);
}
}

- (NSManagedObjectContext *)getContextWithDateModel:(NSString *)dataModel
{
//1.创建模型文件［相当于数据库里的表］
//2.添加实体   ［一张表］
//3.创建实体类 ［相当于模型］
//4.生成上下文 关联模型文件生成数据库
//4.1上下文
NSManagedObjectContext *context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
//4.2持久化存储协调器
NSURL *componryURL = [[NSBundle mainBundle] URLForResource:dataModel withExtension:nil];
NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:componryURL];
NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
//4.3设置数据库路径
NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *sqliteName = [[dataModel componentsSeparatedByString:@"."] firstObject];
NSString *sqlitePath = [doc stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.sqlite",sqliteName]];
NSLog(@"%@",sqlitePath);
[store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:[NSURL fileURLWithPath:sqlitePath] options:nil error:nil];
context.persistentStoreCoordinator = store;
return context;

/*在写以上代码的时候，先初始化上下文，再初始化上下文需要的持久化存储协调器，再初始化持久化存储协调器所需要的模型文件，最后添加持久化类型和文件路径。个人感觉按照这个方法比较容易记忆。
*/

}

@end