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.
解决方法
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,不使用removePersistentStore,我不在乎,因为我稍后会重建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;
}
