iOS CoreData 开发

新年新气象，曾经的妹子结婚了，而光棍的我决定书写博客~ 废话结束。

本人不爱使用第三方的东东，喜欢原汁原味的官方版本，本次带来CoreData数据存储篇~

 

创建应用

勾上Use Core Data,不勾也行，后面再添加上去一样的

点击coredata文件，look下

添加实体，点击下面的Add Entity即可，或者通过菜单操作，效果一样。

 

创建一个实体类

 

 

接着，生成代码：

点击Create NSManagedObject Subclass ....,然后选择我们的User，生成代码

 

写代码之前，先来点介绍吧，主要涉及到下面三个东东

1、Managed Object Model ， 理解成数据库吧，存储了Entity,就是你要存储的东西

2、Persistent Store Coordinate， 理解成数据库连接吧，里面存放了数据存储到具体的文件等等信息

3、Managed Object Context， 数据上下文，基本上所有的操作都是通过这个的。

 

下面进入写代码状态：

 上面三个对象，一个不可少，所以，先来初始化之类的操作吧

 

///定义三个属性


@property(strong,nonatomic) NSManagedObjectModel *cdModel;
@property(strong,nonatomic) NSManagedObjectContext *cdContext;
@property(strong,nonatomic) NSPersistentStoreCoordinator *cdCoordinator;

- (NSManagedObjectModel *)cdModel
{
    if(!_cdModel)
    {
        _cdModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    }
    
    return _cdModel;
}

- (NSPersistentStoreCoordinator *)cdCoordinator
{
    if(!_cdCoordinator)
    {
        //find the database
        NSString *dirPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:DBNAME];
        NSURL *dbPath = [NSURL fileURLWithPath:dirPath];
        NSError *err;
        _cdCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.cdModel];
        if(![_cdCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:dbPath options:nil error:&err])
        {
            NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);
        }
        dirPath = nil;
        dbPath = nil;
    }
    return _cdCoordinator;
}

- (NSManagedObjectContext *)cdContext
{
    if(!_cdContext)
    {
        _cdContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
        [_cdContext setPersistentStoreCoordinator:self.cdCoordinator];
    }
    return _cdContext;
}

下面进行CRUD操作

- (void)insertToDB:(NSString *)username password:(NSString *)password
{
    User *u = (User *)[NSEntityDescription insertNewObjectForEntityForName:TBNAME inManagedObjectContext:self.cdContext];
    u.username = username;
    u.password = password;
    NSError *err;
    if(![self.cdContext save:&err])
    {
        NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);
    }
}

- (void)readFromDb
{
    NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:TBNAME inManagedObjectContext:self.cdContext];
    [fetch setEntity:entity];
    NSError* err;
    NSArray *results = [self.cdContext executeFetchRequest:fetch error:&err];
    if(err)
    {
        NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);
        return;
    }
    [results enumerateObjectsUsingBlock:^(User  *_Nonnull user, NSUInteger idx, BOOL * _Nonnull stop) {
        NSLog(@"----%@   %@",user.username,user.password);
    }];
}

好的，来测试下：

 

算了，时间来不及了，要睡觉了，就不啰嗦了，下面是完整代码

//
//  ViewController.m
//  CoreDataTest
//
//  Created by winter on 16/2/14.
//  Copyright © 2016年 winter. All rights reserved.
//

#import "ViewController.h"
#import <CoreData/CoreData.h>
#import "User.h"

/// define database name
#define DBNAME @"CoreDataTest.sqlite"
/// define entity
#define TBNAME @"User"


@interface ViewController ()
{
    
}
///定义三个属性


@property(strong,nonatomic) NSManagedObjectModel *cdModel;
@property(strong,nonatomic) NSManagedObjectContext *cdContext;
@property(strong,nonatomic) NSPersistentStoreCoordinator *cdCoordinator;


@end

@implementation ViewController

#pragma mark - 实现三个属性的getter Method

- (NSManagedObjectModel *)cdModel
{
    if(!_cdModel)
    {
        _cdModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    }
    
    return _cdModel;
}

- (NSPersistentStoreCoordinator *)cdCoordinator
{
    if(!_cdCoordinator)
    {
        //find the database
        NSString *dirPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:DBNAME];
        NSURL *dbPath = [NSURL fileURLWithPath:dirPath];
        NSError *err;
        _cdCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.cdModel];
        if(![_cdCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:dbPath options:nil error:&err])
        {
            NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);
        }
        dirPath = nil;
        dbPath = nil;
    }
    return _cdCoordinator;
}

- (NSManagedObjectContext *)cdContext
{
    if(!_cdContext)
    {
        _cdContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
        [_cdContext setPersistentStoreCoordinator:self.cdCoordinator];
    }
    return _cdContext;
}


#pragma mark - crud
- (void)insertToDB:(NSString *)username password:(NSString *)password
{
    User *u = (User *)[NSEntityDescription insertNewObjectForEntityForName:TBNAME inManagedObjectContext:self.cdContext];
    u.username = username;
    u.password = password;
    NSError *err;
    if(![self.cdContext save:&err])
    {
        NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);
    }
}

- (void)readFromDb
{
    NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:TBNAME inManagedObjectContext:self.cdContext];
    [fetch setEntity:entity];
    NSError* err;
    NSArray *results = [self.cdContext executeFetchRequest:fetch error:&err];
    if(err)
    {
        NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);
        return;
    }
    [results enumerateObjectsUsingBlock:^(User  *_Nonnull user, NSUInteger idx, BOOL * _Nonnull stop) {
        NSLog(@"----%@   %@",user.username,user.password);
    }];
}


- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self insertToDB:@"wang" password:@"password"];
    
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self readFromDb];
}

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

@end