我需要删除所有用户信息并重新创建它。我用它来创造一切的代码在应用程序的委托:重新创建CoreData时的上下文问题
- (NSManagedObjectContext *)managedObjectContext {
if (managedObjectContext != nil) {
return managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext = [[NSManagedObjectContext alloc] init];
[managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return managedObjectContext;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
if (persistentStoreCoordinator != nil) {
return persistentStoreCoordinator;
}
NSString* dir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES) lastObject];
NSURL *storeURL = [NSURL fileURLWithPath: [dir stringByAppendingPathComponent:
@"Data.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;
}
然后,我删除了一切:
[context reset];
NSString* dir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES) lastObject];
NSURL *storeURL = [NSURL fileURLWithPath: [dir stringByAppendingPathComponent:
@"Data.sqlite"]];
NSError *error;
NSURL *storeURL = store.URL;
NSPersistentStoreCoordinator *storeCoordinator = [((CustomAppDelegate *)[[UIApplication sharedApplication] delegate]) persistentStoreCoordinator];
NSPersistentStore *store = [[storeCoordinator persistentStores] objectAtIndex:0];
[storeCoordinator removePersistentStore:store error:&error];
[[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:&error];
[storeCoordinator release];
storeCoordinator = nil;
而且似乎工作,问题是当我尝试保存新数据,之后。如果我这样做:
NSManagedObjectContext *afterContext = [appDelegate managedObjectContext];
NSEntityDescription *userEntity = [NSEntityDescription entityForName:@"User"
inManagedObjectContext:afterContext];
NSManagedObject *user = [NSEntityDescription
insertNewObjectForEntityForName:[userEntity name] inManagedObjectContext:afterContext];
[user setValue:@"John" forKey:@"firstName"];
if(![afterContext save:&error])
NSLog(@"oops");
崩溃在afterContext保存,它gaves我EXC_BAD_INSTUCTION例外。当我做 [appDelegate managedObjectContext]它创建新的persistentStore,所以我不知道可能是什么问题。对前一个对象的引用?堆栈跟踪根本没有提供任何线索。
感谢您的提示!让所有事情都在委托中进行并设置上下文无(之后重新创建)解决了所有问题。 PS:你的回答让我想到了指针,为什么我需要在代表中这么做,真的如此:谢谢! – ferostar