1. 创建项目

2. 创建CoreDataManager来管理

MTCoreDataManager.h文件

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
@interface MTCoreDataManager : NSObject

// 创建一个管理对象上下文
@property (nonatomic, strong) NSManagedObjectContext *managerContext;

// 单例
+ (instancetype)sharedManager;
@end

MTCoreDataManager.m文件

#import "MTCoreDataManager.h"

@implementation MTCoreDataManager
static MTCoreDataManager *sharedManager;
// 单例
+ (instancetype)sharedManager {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedManager = [MTCoreDataManager new];
    });
    return sharedManager;
}

// 创建一个管理对象上下文
- (NSManagedObjectContext *)managerContext {
    if (_managerContext == nil) {
        // 创建对象
        _managerContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
        
        // 给上下文设置持久化存储协调器
        // 模型文件url
        NSURL *url = [[NSBundle mainBundle] URLForResource:@"Person" withExtension:@"momd"];
        // 根据url获取到模型文件
        NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:url];
        // 设置模型文件
        NSPersistentStoreCoordinator *persitent = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
        
        // 数据路径放置在沙盒
        NSArray *documentArr =  NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
        NSString *documentPath = [[documentArr firstObject] stringByAppendingPathComponent:@"person.db"];
        NSLog(@"%@", documentPath);
        // 获取文件路径的url
        NSURL *pathUrl = [NSURL fileURLWithPath:documentPath];
        // 添加数据库文件路径
        [persitent addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:pathUrl options:nil error:nil];
        // 设置持久化存储协调器
        [_managerContext setPersistentStoreCoordinator:persitent];
    }
    return _managerContext;
}

@end

3. 创建CoreData

右键项目->New File...->Core Data->Data Model->修改类名->点击create.

图1.png

4. 创建实体类

点击上一步新建的Person.xcdatamodeld文件，选择左下角的Add Entity，接下来自己可修改实体名，并在右侧添加属性。

图2.png

5. 创建NSManagedObjectModel实体类

右键项目->Core Data->NSManagedObjectObject subclass->选择Person->next->next->create。创建好之后项目结构如下：

图2.png

6. 插入数据

// 插入
- (IBAction)insert {
    // 通过实体描述出实体对象
    Person *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:[MTCoreDataManager sharedManager].managerContext];
    person.name = @"mazaiting";
    person.age = @(24);
    // 提交数据
    [[MTCoreDataManager sharedManager].managerContext save:nil];
    NSLog(@"插入成功");
}

7. 查询数据

// 查询
- (IBAction)fetch {
    // 查询请求
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    
    // 设置参数
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:[MTCoreDataManager sharedManager].managerContext];
    // 设置实体
    request.entity = entity;
    // 谓词--类似于sql中的where
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age = %d", 24];
    // 设置谓词
    request.predicate = predicate;
    // 排序
    NSSortDescriptor *sort = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
    // 设置排序
    request.sortDescriptors = @[sort];
    // 执行查询请求
    NSArray *arr = [[MTCoreDataManager sharedManager].managerContext executeFetchRequest:request error:nil];
    if (arr.count == 0) {
        NSLog(@"表中无数据");
    }
    // 打印结果
    for (Person *person in arr) {
        NSLog(@"name: %@, age: %@", person.name, person.age);
    }
}

8. 更新数据

// 更新
- (IBAction)update {
    // 创建请求
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    // 设置参数
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:[MTCoreDataManager sharedManager].managerContext];
    // 设置实体
    request.entity = entity;
    // 设置谓词
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age = %d", 24];
    request.predicate = predicate;
    // 执行请求
    NSArray *arr = [[MTCoreDataManager sharedManager].managerContext executeFetchRequest:request error:nil];
    
    for (Person *person in arr) {
        person.name = @"zaiting";
    }
    
    [[MTCoreDataManager sharedManager].managerContext save:nil];
    NSLog(@"更新成功");
}

9. 删除数据

// 删除
- (IBAction)delete {
    // 创建请求
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    // 获取实体
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:[MTCoreDataManager sharedManager].managerContext];
    // 设置实体
    request.entity = entity;
    // 创建谓词
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age = %d", 24];
    // 设置谓词
    request.predicate = predicate;
    // 执行命令
    NSArray *arr = [[MTCoreDataManager sharedManager].managerContext executeFetchRequest:request error:nil];
    for (Person *person in arr) {
        [[MTCoreDataManager sharedManager].managerContext deleteObject:person];
    }
    NSLog(@"删除成功");
}

10. 整个流程打印

图3.png