Core Data uses

A brief introduction to the iOS data persistence Core uses

Words don't say much, direct

Next, command+n the new core Data file in the project

After the creation is successful, then edit the core Data file

Next, add attributes to the entity

Generate the corresponding model according to the added attributes

The User entity ticked the next step

The project will automatically generate the User's model

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>


@interface User:nsmanagedobject

@property (nonatomic, retain) NSString * username;
@property (nonatomic, retain) nsnumber * age;

@end

#import "User.h"

@implementation User

Dynamic dynamically generated settings or methods for accessing properties
@dynamic username;
@dynamic age;

@end

The next simple implementation of the database to add a message, to implement this feature requires a Mac or notebook installed

#import "ViewController.h"
#import <coredata/coredata.h>// Remember to import the core Data framework
#import "User.h"

#define Coredata_path [Nshomedirectory () stringbyappendingstring:@ "/library/Coredata.sqlite"]//sandbox path


@interface Viewcontroller ()
{

Nsmanagedobjectcontext *context;//File Management Objects
}
@end

@implementation Viewcontroller

-(void) Viewdidload {
[Super Viewdidload];


NSString *storepath=[nshomedirectory () stringbyappendingstring:@ "/library/Coredata.sqlite"];

NSLog (@ "%@", storepath);//Print the sandbox path of the database file
1. Connect and open the database
[Self opendatabase];


2. Add Data
[Self addUser];

}

-(void) OpenDatabase
{
//1. Create a data model object
Nsurl *mourl=[[nsbundle Mainbundle] urlforresource:@ "Model" withextension:@ "MOMD"];
Data Model objects
Nsmanagedobjectmodel * Managermodel=[[nsmanagedobjectmodel alloc] initwithcontentsofurl:mourl];


//2. Creating a local persisted file object

Nspersistentstorecoordinator *persist=[[nspersistentstorecoordinator Alloc] Initwithmanagedobjectmodel: Managermodel];
/*
Nssqlitestoretype is stored as a database type (and XML type storage)
URLs stored in sandboxed paths
*/
NSString *storepath=[nshomedirectory () stringbyappendingstring:@ "/library/coredata.sqlite"];
//

Nsurl *storeurl=[nsurl Fileurlwithpath:coredata_path];

Nserror *error=nil;

To add a data object to the databaseNssqlitestoretypeThis isSQLiteof the database type
[Persist Addpersistentstorewithtype:Nssqlitestoretype
Configuration:nil
Url:storeurl
Options:nil
error:&error];

if (Error) {

NSLog (@ "Database open failed");
}

//3. Creating a File Management Object
Context=[[nsmanagedobjectcontext alloc] init];

Managing local persisted file objects
[Context Setpersistentstorecoordinator:persist];

}


Add user
-(void) AddUser
{
Create Model Entities
(1) The name of the entity
(2) File Management Objects
user *user=[nsentitydescription insertnewobjectforentityforname:@ "user" inmanagedobjectcontext:context];
[Email protected] "Jack";
[Email protected];

Set to the File Management Objects container
(1) Nsmanagedobject object user-> is its entity
[Context Insertobject:user];
Save to Database
BOOL Result=[context Save:nil];

if (result) {

NSLog (@ "add success");
}else
{
NSLog (@ "Add failed");
}

}

The Core Data is briefly introduced here. The next update will continue.

Core Data uses