如何删除核心数据持久性存储

Question

我需要删除我的持久存储(按对象执行它不实用,因为我有超过100,000个对象).我试过这个:

- (IBAction)resetDatabase:(id)sender {

    NSPersistentStore* store = [[__persistentStoreCoordinator persistentStores] lastObject];

    NSError *error = nil;
    NSURL *storeURL = store.URL;

    // release context and model
    [__managedObjectContext release];
    [__managedObjectModel release];
    __managedObjectModel = nil;
    __managedObjectContext = nil;

    [__persistentStoreCoordinator removePersistentStore:store error:nil];

    [__persistentStoreCoordinator release];
    __persistentStoreCoordinator = nil;

    [[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:&error];
    if (error) {
        NSLog(@"filemanager error %@", error);
    }    

     // recreate the stack
     __managedObjectContext = [self managedObjectContext];

}

但是当我尝试之后将实体插入商店时,我收到此错误:

This NSPersistentStoreCoordinator has no persistent stores.  It cannot perform a save operation.

更新: 我尝试在删除持久存储之前释放MOC和MOM,但我仍然得到相同的错误.

Answer 1

以下是我在多个应用中执行"重置数据"功能的方法:

- (void)reset {
  // Release CoreData chain
  [_managedObjectContext release];
  _managedObjectContext = nil;
  [_managedObjectModel release];
  _managedObjectModel = nil;
  [_persistentStoreCoordinator release];
  _persistentStoreCoordinator = nil;

  // Delete the sqlite file
  NSError *error = nil;
  if ([fileManager fileExistsAtPath:_storeURL.path])
    [fileManager removeItemAtURL:_storeURL error:&error];
  // handle error...
}

基本上我只是释放CoreData链,然后删除persistentStore文件.这就是你要做的事情,没有使用removePersistentStore,我不在乎,因为我稍后将重建persistentStore协调器.然后在下一个核心数据调用时,使用单独的惰性样式构造函数透明地重建链,例如:

- (NSManagedObjectModel *) managedObjectModel {
  if (!_managedObjectModel)
    _managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];
  return _managedObjectModel;
}