IOS-CoreData（增删改查、表关联、分页和模糊查询、多个数据库）

1>什么是CoreData

Core Data是iOS5之后才出现的一个框架，它提供了对象-关系映射(ORM)的功能，即能够将OC对象转化成数据，保存在SQLite数据库文件中，也能够将保存在数据库中的数据还原成OC对象。在此数据操作期间，我们不需要编写任何SQL语句，这个有点类似于著名的Hibernate持久化框架，不过功能肯定是没有Hibernate强大的。

 

 

 

2>CoreData的使用步骤

 

1.创建模型文件

2.添加实体

3.创建实体类

4.生成上下文 关联模型文件生成数据库

5.保存对象到数据库

6.从数据库获取对象

7.更新数据

8.删除数据

 

3>打开CoreData的SQL语句输出开关

 

1.打开Product，点击EditScheme...

2.点击Arguments，在ArgumentsPassed On Launch中添加2项

   1> -com.apple.CoreData.SQLDebug

   2> 1

 

一、CoreData基本使用-增删改查和表关联

 //
 //  ViewController.m
 //  IOS_0121_CoreData
 //
 //  Created by ma c on 16/1/21.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

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

 @interface ViewController ()

 @property (nonatomic, strong) NSManagedObjectContext *context;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];
     //1.创建模型文件（相当于数据库中的表）
     //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

     //上下文
     self.context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
     //模型数据文件
     NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

     //持久化存储器
     //把数据保存到一个文件，而不是内存
     NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
     //数据名字和路径
     NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
     NSString *sqlitePath = [path stringByAppendingPathComponent:@"company.sqlite"];
     NSLog(@"%@",sqlitePath);

     NSURL *url = [NSURL fileURLWithPath:sqlitePath];
     [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];

     self.context.persistentStoreCoordinator = store;

 }
 //数据库操作ADUQ （ADD、Delete、Update、Query）
 #pragma mark - 添加员工
 - (IBAction)addEmployee
 {
     Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];

     emp.name = @"bowen";
     emp.height = @"";
     emp.birthday = [NSDate date];

     //直接保存
     NSError *error = nil;
     [self.context save:&error];

     if (error) {
         NSLog(@"%@",error);
     }
 }

 #pragma mark - 查询员工
 - (IBAction)searchEmployee
 {
     //1.NSFetchRequest 抓取请求对象
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
     //2.设置过滤条件
     NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"bowen"];
     request.predicate = pre;
     //3.排序
     NSSortDescriptor *heightSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
     request.sortDescriptors = @[heightSort];
     //4.执行请求
     NSError *error = nil;
     NSArray *emps = [self.context executeFetchRequest:request error:&error];

     if (error) {
         NSLog(@"%@",error);
     }

     for (Employee *emp in emps) {
         NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
     }
 }

 #pragma mark - 更新员工
 - (IBAction)updateEmployee
 {
     //1.查找
     //获取对象
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
     //设置过滤条件
     NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"bowen"];
     request.predicate = pre;
     //执行请求
     NSArray *emps = [self.context executeFetchRequest:request error:nil];

     //2.更新
     for (Employee *emp in emps) {
         emp.height = @"";
     }
     //3.保存
     [self.context save:nil];
 }

 #pragma mark - 删除员工
 - (IBAction)deleteEmployee
 {
     //1.查找
     //获取对象
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
     //设置过滤条件
     NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"bowen"];
     request.predicate = pre;
     //执行请求
     NSArray *emps = [self.context executeFetchRequest:request error:nil];

     //2.删除
     for (Employee *emp in emps) {
         [self.context deleteObject:emp];
     }

     //3.保存
     [self.context save:nil];
 }

 #pragma mark - 表关联
 - (IBAction)AddRelationship
 {
     //创建两个部门：IOS、Android
     Department *IOSDepart = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.context];
     IOSDepart.departNo = @"";
     IOSDepart.name = @"IOS";
     IOSDepart.createDate = [NSDate date];

     Department *AndroidDepart = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.context];
     AndroidDepart.departNo = @"";
     AndroidDepart.name = @"Android";
     AndroidDepart.createDate = [NSDate date];

     //创建两个员工：bowen1，bowen2
     Employee *emp1 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];
     emp1.name = @"bowen1";
     emp1.height = @"";
     emp1.birthday = [NSDate date];
     emp1.depart = IOSDepart;

     Employee *emp2 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];
     emp2.name = @"bowen2";
     emp2.height = @"";
     emp2.birthday = [NSDate date];
     emp2.depart = AndroidDepart;

     //保存
     [self.context save:nil];
 }

 - (IBAction)searchRelationship
 {
     //读取IOS部门员工

     //1.NSFetchRequest 抓取请求对象
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
     //2.设置过滤条件
     NSPredicate *pre = [NSPredicate predicateWithFormat:@"depart.name = %@",@"IOS"];
     request.predicate = pre;
     //3.执行请求
     NSError *error = nil;
     NSArray *emps = [self.context executeFetchRequest:request error:&error];

     if (error) {
         NSLog(@"%@",error);
     }

     for (Employee *emp in emps) {
         NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
     }

 }

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

 @end

三、分页查询和模糊查询

 //
 //  ViewController.m
 //  IOS_0121_CoreData
 //
 //  Created by ma c on 16/1/21.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

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

 @interface ViewController ()

 @property (nonatomic, strong) NSManagedObjectContext *context;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];
     //1.创建模型文件（相当于数据库中的表）
     //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

     //上下文
     self.context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
     //模型数据文件
     NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

     //持久化存储器
     //把数据保存到一个文件，而不是内存
     NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
     //数据名字和路径
     NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
     NSString *sqlitePath = [path stringByAppendingPathComponent:@"company.sqlite"];
     NSLog(@"%@",sqlitePath);

     NSURL *url = [NSURL fileURLWithPath:sqlitePath];
     [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];

     self.context.persistentStoreCoordinator = store;

 }
 //数据库操作ADUQ （ADD、Delete、Update、Query）
 #pragma mark - 添加员工
 - (IBAction)addEmployee
 {

     for (int i = ; i < ; i++) {
         Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];
         emp.name = [NSString stringWithFormat:@"bowen%d",i];
         emp.height = [NSString stringWithFormat:@"%d",+i];
         emp.birthday = [NSDate date];

     }

     //直接保存
     NSError *error = nil;
     [self.context save:&error];

     if (error) {
         NSLog(@"%@",error);
     }
 }

 #pragma mark - 分页查询
 - (IBAction)pagingAndQuerying
 {
     //1.NSFetchRequest 抓取请求对象
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];

     //2.排序
     NSSortDescriptor *heightSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
     request.sortDescriptors = @[heightSort];

     //3.分页查询
     //分页的起始索引
     request.fetchOffset = ;
     //分页的条数
     request.fetchLimit = ;

     //4.执行请求
     NSError *error = nil;
     NSArray *emps = [self.context executeFetchRequest:request error:&error];

     if (error) {
         NSLog(@"%@",error);
     }

     for (Employee *emp in emps) {
         NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
     }
 }

 - (IBAction)fuzzyQuery
 {
     //1.NSFetchRequest 抓取请求对象
     NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];

     //2.排序
     NSSortDescriptor *heightSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
     request.sortDescriptors = @[heightSort];

     //3.模糊查询
     //名字以“bowen1”开头
     //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name BEGINSWITH %@",@"bowen1"];
     //request.predicate = pre;

     //名字以“1”结尾
     //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name ENDSWITH %@",@"1"];
     //request.predicate = pre;

     //名字包含“wen1”结尾
     //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name CONTAINS %@",@"1"];
     //request.predicate = pre;

     //like
     //名字以“1”结尾
     //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name like %@",@"*wen14"];
     //request.predicate = pre;

     //名字以“bowen2”开头
     NSPredicate *pre = [NSPredicate predicateWithFormat:@"name like %@",@"bowen2*"];
     request.predicate = pre;

     //4.执行请求
     NSError *error = nil;
     NSArray *emps = [self.context executeFetchRequest:request error:&error];

     if (error) {
         NSLog(@"%@",error);
     }

     for (Employee *emp in emps) {
         NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
     }
 }

 @end

三、创建多个数据库

 //
 //  ViewController.m
 //  IOS_0121_CoreData
 //
 //  Created by ma c on 16/1/21.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

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

 @interface ViewController ()

 @property (nonatomic, strong) NSManagedObjectContext *companyContext;
 @property (nonatomic, strong) NSManagedObjectContext *weibocontext;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

     //一个数据库对应着一个上下文
     self.companyContext = [self setupContextWithModelName:@"Company"];
     self.weibocontext = [self setupContextWithModelName:@"weibo"];

 }

 //根据模型文件返回上下文
 - (NSManagedObjectContext *)setupContextWithModelName:(NSString *)modelName
 {
     //1.创建模型文件（相当于数据库中的表）
     //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

     //上下文
     NSManagedObjectContext *context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];

     //模型数据文件
     //使用下面的方法，如果boundles为空，会把boundles里面所有的模型文件的表都放在一个数据库中
     //NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

     NSLog(@"%@",[[NSBundle mainBundle] bundlePath]);

     NSURL *modelURL = [[NSBundle mainBundle] URLForResource:modelName withExtension:@"momd"];
     NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

     //持久化存储器
     //把数据保存到一个文件，而不是内存
     NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];

     //数据名字和路径
     NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

     NSString *sqlliteName = [NSString stringWithFormat:@"%@.sqllite",modelName];

     NSString *sqlitePath = [path stringByAppendingPathComponent:sqlliteName];
     NSLog(@"%@",sqlitePath);

     NSURL *url = [NSURL fileURLWithPath:sqlitePath];
     [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];

     context.persistentStoreCoordinator = store;

     return context;

 }
 //数据库操作ADUQ （ADD、Delete、Update、Query）
 #pragma mark - 添加
 - (IBAction)add
 {
     Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.companyContext];
     emp.name = @"bowen";
     emp.height = @"";
     emp.birthday = [NSDate date];

     Status *status = [NSEntityDescription insertNewObjectForEntityForName:@"Status" inManagedObjectContext:self.weibocontext];
     status.text = @"回家";
     status.createDate = @"2015-01-28";

     [self.companyContext save:nil];
     [self.weibocontext save:nil];

 }

 #pragma mark - 查询
 - (IBAction)querying
 {

 }

 @end