在迁移时使用“对象不能为零”从iCloud迁移到本地崩溃的应用程序-使用核心数据

Question

I have an iOS 7 only app which uses Core Data for storage and I am bringing iCloud, with a switch to the app.

Every aspect of the iCloud integration is working, except the migration from the iCloud Store to the Local store if the user turns off iCloud from within the app.

Through the use of an Exception Breakpoint , the app is crashing with:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM replaceObjectAtIndex:withObject:]: object cannot be nil'

This is crashing at the " migratePersistentStore " code.

This is the code that performs that:

- (void)migrateiCloudStoreToTheLocalStoreAfterUserTurnedOffiCloudInSettings
{    
    // So we can see what's going on, we'll write out the current store URL before the migration
    NSURL *storeURL = [self.persistentStoreCoordinator.persistentStores.lastObject URL];
    NSLog(@"Current Store URL (before iCloud to Local migration): %@", [storeURL description]);

    //    NSPersistentStore *currentStore =     self.persistentStoreCoordinator.persistentStores.lastObject;

    NSPersistentStore *currentStore = [[self.persistentStoreCoordinator persistentStores] firstObject];
    // We'll create a new URL
    NSURL *localURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Envylope.sqlite"];

    NSDictionary *localStoreOptions = nil;
    localStoreOptions = @{ NSPersistentStoreRemoveUbiquitousMetadataOption : @YES,
                           NSMigratePersistentStoresAutomaticallyOption : @YES,
                           NSInferMappingModelAutomaticallyOption : @YES};

    NSError *error = nil;
    [self.persistentStoreCoordinator migratePersistentStore:currentStore
                                                      toURL:localURL
                                                    options:localStoreOptions
                                                   withType:NSSQLiteStoreType error:&error];

    NSLog(@"Current Store URL (after iCloud to Local migration): %@", [localURL description]);

    // We'll write out a NSError here to see if there were any errors during the migration
    NSLog(@"Error from iCloud to local migration %@", error);

    // We'll just do a quick check to make sure are no errors with this procedure.
    NSLog(@"Erros's after all of that %@", error);

    NSLog(@"Current Store URL (after everything): %@", [localURL description]);

    [self removeCloudObservers];
}

Issue

The app will crash, with the error above, at the migratePersistentStore line above. I cannot figure out what to do to get this working.

The commented out code for the currentStore shows that I've also tried checking for the lastObject, instead of the firstObject, and in both cases, I'm getting the same result.

I don't get any crashes from the local to iCloud because I want to make sure, if the user is using iCloud but then chooses not to, their data should be migrated locally.

This ( Migrate Persistant Store Crash ) Stack Overflow question seems like it would be a perfect fit, but firstly the answer isn't accepted and there's no confirmation that the code works from the person asking the question and also, that code didn't work for me; it simply removed the data.

Any guidance on this would really be appreciated.

Answer 1

With paying close attention to the link : Migrate Persistant Store Crash , I was able to get this working with the following code:

NSPersistentStoreCoordinator * persistentStoreCoordinator = self.persistentStoreCoordinator;

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

if([[NSFileManager defaultManager]fileExistsAtPath:localURL.path])
{
    NSLog(@"File exists");
    [[NSFileManager defaultManager] removeItemAtPath:localURL.path error:&error];
    NSLog(@"Removing error = %@", error); 

}

[[NSFileManager defaultManager] copyItemAtPath:persistentStore.URL.path toPath:localURL.path error:&error];

NSLog(@"The copying error = %@", error);

NSPersistentStoreCoordinator * newPersistentStoreCoordinator;

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

[newPersistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType

                                            configuration:nil

                                                      URL:localURL

                                                  options:localStoreOptions

                                                    error:&error];

NSLog(@"The adding error = %@", error);

Hopefully this will help someone with the same issue