1、筆者認(rèn)為core data就是ios內(nèi)置的一個(gè)操作sqlite的框架。
a、首先了解Core data的基本信息
在創(chuàng)建工程的時(shí)候，勾選user core data可以直接生成一些操作coreData的方法
創(chuàng)建《Data Model》生成創(chuàng)建表（實(shí)體）、屬性、聯(lián)系的文件。創(chuàng)建《NSManagedObject subclass》可直接生成表屬性中的get，set方法，在實(shí)體文件中
需要注意的地方：（“實(shí)體名Dog”也是“表名”）
在使用代碼操作coredata框架前，先了解core data中的幾個(gè)重要對(duì)象和重要操作
操作：
a、添加CoreData框架
b、導(dǎo)入#import<CoreData/CoreData.h>
對(duì)象：
1、NSManagedObjectContext 管理對(duì)象，上下文，持久性存儲(chǔ)模型對(duì)象
2、NSManagedObjectModel 被管理的數(shù)據(jù)模型，[數(shù)據(jù)結(jié)構(gòu)](http://lib.csdn.net/base/31)
3、NSPersistentStoreCoordinator 連接數(shù)據(jù)庫(kù)的
4、NSManagedObject 被管理的數(shù)據(jù)記錄
5、NSFetchRequest 數(shù)據(jù)請(qǐng)求
6、NSEntityDescription 表格實(shí)體結(jié)構(gòu)
注意：
tip1：需要知道.xcdatamodel文件編譯后為.momd或者.mom文件。
tip2：core data的數(shù)據(jù)文件生成在沙盒的document文件夾下面。
b、使用core data的個(gè)人琢磨步驟
tip1：創(chuàng)建《Data Model》文件（Animations）。
tip2：在Animations中創(chuàng)建一個(gè)實(shí)體（表）Animate。
tip3：創(chuàng)建《NSManagedObject subclass》文件，生成Animate的屬性文件AnimateEntity。
tip4：編寫操縱core data框架的oc代碼，即entity的管理文件AnimateEntityManager。
下面貼出，筆者實(shí)現(xiàn)AnimateEntityManager的代碼
#import <Foundation/Foundation.h>
#import "AnimateEntity.h"
@interface AnimateEntityManager : NSObject
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;
//插入數(shù)據(jù)
- (void)insertCoreData:(NSMutableArray*)dataArray;
//查詢
- (NSMutableArray*)selectData:(int)pageSize andOffset:(int)currentPage;
//刪除
- (void)deleteData;
//更新
- (void)updateData:(NSString*)newsId withIsLook:(NSString*)islook;
@end
#import "AnimateEntityManager.h"
@import CoreData;
#define TableName @"AnimateEntity"
@implementation AnimateEntityManager
@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
- (void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
}
#pragma mark - Core Data stack
// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
- (NSManagedObjectContext *)managedObjectContext
{
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
_managedObjectContext = [[NSManagedObjectContext alloc] init];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return _managedObjectContext;
}
// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the application's model.
- (NSManagedObjectModel *)managedObjectModel
{
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Animations" withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the application's store added to it.
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Animations.sqlite"];
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
#pragma mark - Application's Documents directory
// Returns the URL to the application's Documents directory.獲取Documents路徑
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
//插入數(shù)據(jù)
- (void)insertCoreData:(NSMutableArray*)dataArray
{
// NSLog(@"%@",NSHomeDirectory());
NSManagedObjectContext *context = [self managedObjectContext];
for (AnimateEntity *entity in dataArray) {
AnimateEntity *entityInfo = [NSEntityDescription insertNewObjectForEntityForName:TableName inManagedObjectContext:context];
entityInfo.term = entity.term;
entityInfo.termUnit = entity.termUnit;
NSError *error;
if(![context save:&error])
{
NSLog(@"不能保存：%@",[error localizedDescription]);
}
}
}
//查詢
- (NSMutableArray*)selectData:(int)pageSize andOffset:(int)currentPage
{
NSManagedObjectContext *context = [self managedObjectContext];
// 限定查詢結(jié)果的數(shù)量
//setFetchLimit
// 查詢的偏移量
//setFetchOffset
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setFetchLimit:pageSize];
[fetchRequest setFetchOffset:currentPage];
NSEntityDescription *entity = [NSEntityDescription entityForName:TableName inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSError *error;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
NSMutableArray *resultArray = [NSMutableArray array];
for (AnimateEntity *info in fetchedObjects) {
NSLog(@"interestBearingtime:%@", info.interestBearingtime);
NSLog(@"projectName:%@", info.projectName);
[resultArray addObject:info];
}
return resultArray;
}
//刪除
-(void)deleteData
{
NSManagedObjectContext *context = [self managedObjectContext];
NSEntityDescription *entity = [NSEntityDescription entityForName:TableName inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setIncludesPropertyValues:NO];
[request setEntity:entity];
NSError *error = nil;
NSArray *datas = [context executeFetchRequest:request error:&error];
if (!error && datas && [datas count])
{
for (NSManagedObject *obj in datas)
{
[context deleteObject:obj];
}
if (![context save:&error])
{
NSLog(@"error:%@",error);
}
}
}
//更新
- (void)updateData:(NSString*)newsId withIsLook:(NSString*)repaymentMethoud
{
NSManagedObjectContext *context = [self managedObjectContext];
NSPredicate *predicate = [NSPredicate
predicateWithFormat:@"newsid like[cd] %@",newsId];
//首先你需要建立一個(gè)request
NSFetchRequest * request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:TableName inManagedObjectContext:context]];
[request setPredicate:predicate];//這里相當(dāng)于sqlite中的查詢條件，具體格式參考蘋果文檔
//https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Predicates/Articles/pCreating.html
NSError *error = nil;
NSArray *result = [context executeFetchRequest:request error:&error];//這里獲取到的是一個(gè)數(shù)組，你需要取出你要更新的那個(gè)obj
for (AnimateEntity *info in result) {
info.repaymentMethoud = repaymentMethoud;
}
//保存
if ([context save:&error]) {
//更新成功
NSLog(@"更新成功");
}
}
@end
