Migrating a Core Data Store from iCloud to local

Question

I'm currently struggling with Core Data iCloud migration.

I want to move a store from an iCloud ubiquity container (.nosync) to a local URL. The problem is that whenever I call something like this:

[self.persistentStoreCoordinator migratePersistentStore: currentiCloudStore 
                                                  toURL: localURL 
                                                options: nil 
                                               withType: NSSQLiteStoreType 
                                                  error: &error];

I get this error:

-[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:](1055): CoreData: Ubiquity:  Error: A persistent store which has been previously added to a coordinator using the iCloud integration options must always be added to the coordinator with the options present in the options dictionary. If you wish to use the store without iCloud, migrate the data from the iCloud store file to a new store file in local storage. file://localhost/Users/sch/Library/Containers/bla/Data/Documents/tmp.sqlite. This will be a fatal error in a future release

Anyone ever seen this? Maybe I'm just missing the right migration options?

Answer 1

My guess is that, based on the error message, by setting your options to nil, the PSC is unable to move the store. You probably need to get the dictionary of options for the original store and pass those along instead of setting them to nil.

Answer 2

YES, I have this question too.

I want to turn a iCloud store to a local store.

---

Solution 1 :Moving managedObjects one-by-one to the localStore.

But if you have a large database, it will be so slow.

So I found a second solution yesterday.

---

Solution 2: Editing the metadata of the iCloud store,

and saving it to the new location.

After you remove "com.apple.coredata.ubiquity.*" keys in metadata, you'll get a fully local store.

---

Here is my code for solution 2:

There are some properties already set:

@property (nonatomic, strong) NSPersistentStoreCoordinator *coordinator;
@property (nonatomic, strong) NSManagedObjectContext *context;

@property (nonatomic, strong) NSPersistentStore *iCloudStore;
//represent the iCloud store already using 
//(after [coordinator addPersistentStore] you get this NSPersistentStore)

@property (nonatomic, strong) NSURL *iCloudStoreURL;
//represent the iCloud store real location
//(it is the URL you send to the [coordinator addPersistentStore])

@property (nonatomic, strong) NSURL *iCloudStoreLocalVersionURL;
//represent the location of local version store you want to save

And the migrate method:

-(void)migrateCloudStoreToLocalVersion
{
    if(!self.iCloudStore)
        return;

    // remove previous local version
    [FILE_MANAGER removeItemAtURL:self.iCloudStoreLocalVersionURL
                            error:nil];

    // made a copy from original location to the new location
    [FILE_MANAGER copyItemAtURL:self.iCloudStoreURL
                          toURL:self.iCloudStoreLocalVersionURL
                          error:nil];

    //prepare meta data
    NSDictionary *iCloudMetadata = [self.coordinator metadataForPersistentStore:self.iCloudStore].copy;

    NSMutableDictionary *localVersionMetadata = iCloudMetadata.mutableCopy;
    for(NSString * key in iCloudMetadata){
        if([key hasPrefix:@"com.apple.coredata.ubiquity"]){
            [localVersionMetadata removeObjectForKey:key];
        }
    }

    //modify iCloud store
    [self.coordinator setMetadata:localVersionMetadata forPersistentStore:self.iCloudStore];
    [self.coordinator setURL:self.iCloudStoreLocalVersionURL forPersistentStore:self.iCloudStore];

    //save to the localVersion location
    [self.context save:nil];

    //restore iCloud store
    [self.coordinator setMetadata:iCloudMetadata forPersistentStore:self.iCloudStore];
    [self.coordinator setURL:self.iCloudStoreURL forPersistentStore:self.iCloudStore];
}

Then you can use the iCloudStoreLocalVersionURL to using the local version store.

You can use this local version store as local store, without any error.

Note:

Notice the NSStoreUUIDKey in the metadata,

you can optional replace it for the new store.

To mike:

The problem is:

If we use full iCloud options on adding a iCloud store, we'll get all things right but it remains a iCloud store. We here want to turn a iCloud store to local store.

If we add some options except iCloud options, we'll get an error and cannot save any change to this store.

So your answer is not for this problem.

Answer 3

This works for me just fine. I am using NSPersistentDocument and call this method if the user selects Save As menu option. Its also worth noting that I set my own metadata on the file in order to know whether it is synced via iCloud or not. You have to know that in order to pass in the right options when setting up the pac prior to actually opening the store itself. I don't believe there is any API provided for doing this any other way.

// File is NEVER iCloud enabled when we do this.
- (bool)buildNewStoreAtURL:(NSURL*)newURL type:(NSString *)typeName error:(NSError **)error {

    //FLOG(@"buildNewStoreAtURL:type: called");

    NSError *myError;

    // We only have one store
    NSPersistentStore *currentStore = [self.managedObjectContext.persistentStoreCoordinator.persistentStores objectAtIndex:0];
    NSDictionary *currentOptions = currentStore.options;

    // We need to create new options for the new document if it is currently synced via iCloud.
    NSMutableDictionary *newOptions = [[NSMutableDictionary alloc] initWithDictionary:currentOptions];
    [newOptions setObject:@"DELETE" forKey:@"JOURNAL"];

    // Remove any iCloud options
    [newOptions removeObjectForKey:NSPersistentStoreUbiquitousContentNameKey];

    // Instruct to remove any Core Data iCloud metadata
    [newOptions setObject:[NSNumber numberWithBool:YES] forKey:NSPersistentStoreRemoveUbiquitousMetadataOption];


    NSPersistentStoreCoordinator *psc = self.managedObjectContext.persistentStoreCoordinator;

    //FLOG(@"   create a new store at the required URL");
    NSPersistentStore *newStore = [psc migratePersistentStore:currentStore toURL:newURL options:newOptions withType:typeName error:&myError];

    if (newStore) {
        //FLOG(@"   store seems OK");
        // Set our own metadata flags so we can tell of the file is synced via iCloud
        // before we open the store (we have to pass in the right ubiquity name if it is)
        NSDictionary *dict = [self getiCloudMetaDataForStore:[psc metadataForPersistentStore:newStore] iCloud:NO ubiquityName:nil];
        [psc setMetadata:dict forPersistentStore:newStore];
        return YES;
    }
    else {

        FLOG(@" problem creating new document");
        FLOG(@"  - error is %@, %@", myError, myError.userInfo);
        *error = myError;
        return NO;
    }

}

Answer 4

As of iOS 7, there is a much easier and more logical way to migrate stores while dropping iCloud ubiquity, simply pass the NSPersistentStoreRemoveUbiquitousMetadataOption option:

NSDictionary *options = [NSDictionary dictionaryWithObject:@YES
                                                    forKey:NSPersistentStoreRemoveUbiquitousMetadataOption];
[self.persistentStoreCoordinator migratePersistentStore: currentiCloudStore 
                                              toURL: localURL 
                                            options: nil 
                                           withType: NSSQLiteStoreType 
                                              error: &error];

This will migrate the store to the local URL, and drop all iCloud metadata, essentially what @frogcjn did manually.