迁移持久存储崩溃

Question

我有一个开关可以为 iOS 7 应用打开或关闭 iCloud。 iCloud 同步工作正常。当 iCloud 打开并且我将其关闭时，我调用此代码：

- (void)migrateiCloudStoreToLocalStore {

NSError *error;

__weak NSPersistentStoreCoordinator *psc = self.managedObjectContext.persistentStoreCoordinator;

NSDictionary *options = @{NSMigratePersistentStoresAutomaticallyOption:@YES,
                          NSPersistentStoreRemoveUbiquitousMetadataOption : @YES};

NSPersistentStore *currentStore = [psc persistentStores][0];

NSLog(@"iCloud Store - %@", currentStore);

NSLog(@"Local Store - %@", self.store);

[psc migratePersistentStore:currentStore
                      toURL:self.store
                    options:options
                   withType:NSSQLiteStoreType
                      error:&error];

}

我可以看到这两个商店确实存在，但是当调用 migratePersistentStore:toURL:options:withType:error: 时它仍然崩溃。

这是我得到的错误：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM replaceObjectAtIndex:withObject:]: object cannot be nil' *** First throw call stack: (0x2e0a3fd3 0x38850ccf 0x2dfdf29f 0x2de9e7f7 0xa9b61 0xb2305 0xb019f 0x309de05f 0x30a90377 0x3093f6f5 0x308b855b 0x2e06f2a5 0x2e06cc49 0x2e06cf8b 0x2dfd7f4f 0x2dfd7d33 0x32edc663 0x3092316d 0x30289 0x38d5dab7) libc++abi.dylib: terminating with uncaught exception of type NSException

知道为什么会这样吗？这有点奇怪，因为在我的其他设备之一上，它此时并没有崩溃。

Answer 1

试试这个

[psc removePersistentStore:currentStore error:nil];

[psc migratePersistentStore:currentStore
                      toURL:self.store
                    options:options
                   withType:NSSQLiteStoreType
                      error:&error];

[psc addPersistentStoreWithType:NSSQLiteStoreType
                  configuration:nil
                            URL:self.store
                        options:options /* options for local store */
                          error:nil];

更新：新解决方案

NSPersistentStoreCoordinator * persistentStoreCoordinator = self.persistentStoreCoordinator;

NSPersistentStore * persistentStore = [[persistentStoreCoordinator persistentStores] firstObject];

NSMutableDictionary * localStoreOptions = [[self localPersistentStoreOptions] mutableCopy];

[localStoreOptions setObject:@YES forKey:NSPersistentStoreRemoveUbiquitousMetadataOption];

[[NSFileManager defaultManager] copyItemAtPath:persistentStore.URL.path toPath:[self storeURL].path error:nil];

NSPersistentStoreCoordinator * newPersistentStoreCoordinator;

newPersistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

[newPersistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType

                                            configuration:nil

                                                      URL:[self storeURL]

                                                  options:localStoreOptions

                                                    error:nil];

[self setPersistentStoreCoordinator:newPersistentStoreCoordinator];

[self setupManagedObjectContext]; //initialize new moc with new persistent store coordinator