先看概念详解：http://blog.csdn.net/remote_roamer/article/details/7015826
//表格结构 --> NSEntityDescription
//数据库中所有表格和他们的联系 -->NSManagedObjectModel
//数据库存放方式 --> NSPersistentStoreCoordinator
//数据库操作 --> NSManagedObjectContext
//查询语句 --> NSFetchRequest
//表格的记录 --> NSManagedObject
有一个学生类叫Student里面有name ,age,hoby字段
下面用core data对3个字段操作。
-(void) setup{
//初始化model
NSURL *modelURL=[[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"momd"];
self.managedObjectModel=[[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL ] autorelease];
self.persistentStoreCoordinator=[[[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel ] autorelease]; //调节器和model关联起来
NSURL *storeUrl=[NSURL fileURLWithPath:[[self appDocumentDirectory] stringByAppendingPathComponent:@"Model.sqlite"]];
NSError * error=nil;
[self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error];
self.managedObjectContext=[[[NSManagedObjectContext alloc] init ] autorelease ];
[self.managedObjectContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
NSFetchRequest *fetchRequest=[[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription * entity=[NSEntityDescription entityForName:@"Entity" inManagedObjectContext:self.managedObjectContext] ;
//这里entiy名字叫 Entity 自己要添加（这里省略）
[fetchRequest setEntity:entity];
NSSortDescriptor * sort=[[[NSSortDescriptor alloc] initWithKey:@"age" ascending:YES ]autorelease ];
//对象的排序功能
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
self.fetchedResultsController=[[[NSFetchedResultsController alloc]
initWithFetchRequest:fetchRequest
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil] autorelease];
}
-(void)addEmplyee:(NSString *) name age: (NSInteger) age hobby:(NSString *) hooby
{
Student * stu=[NSEntityDescription insertNewObjectForEntityForName:@"Entity" inManagedObjectContext:self.managedObjectContext];
stu.name=name;
stu.age=[NSNumber numberWithInteger:age];
stu.hooby=hooby;
NSError*error=nil;
if(![self.managedObjectContext save:&error])
{
NSLog(@"Save ErrorL %@",[error localizedDescription]);
}
}
-(void)removeEmplyee:(NSString *)name
{
NSFetchRequest *request=[[[NSFetchRequest alloc] init ]autorelease ];
NSEntityDescription * entity=[NSEntityDescription entityForName:@"Entity" inManagedObjectContext:self.managedObjectContext];
[request setEntity:entity];
NSPredicate * predicate=[NSPredicate predicateWithFormat:@"name==[c]%@",name];
[request setPredicate:predicate];
NSError *error=nil;
NSArray * array=[self.managedObjectContext executeFetchRequest:request error:&error];
if(array.count>0)
{
Student * stu=[array objectAtIndex:0];
[self.managedObjectContext deleteObject:stu];
if(![self.managedObjectContext save:&error ])
{
NSLog(@"Save: %@", [error localizedDescription]);
}
}
}
-(NSArray *)fetchAllEmplyee
{
NSError* error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
NSLog(@"performFetch:%@", [error localizedDescription]);
}
return [fetchedResultsController fetchedObjects];
}