From Parse to Core Data: After download complete, how to save image to device!

Hi,

I saved all my data to Parse.com (including vector images as pdf files).

I want to get all this data, save it to a managed object and than save the context. Because getting data in background is asynchronous, i have to wait for download to finish before saving it to core data stack.

I want to use a method for file download operations:

CoreDataStack *coreDataStack = [CoreDataStack defaultStack];
            CardData *cardData = [NSEntityDescription insertNewObjectForEntityForName:@"CardData" inManagedObjectContext:coreDataStack.managedObjectContext];
...
cardData.cardVisual = [self fileDataForStackFromParseFile: [dict objectForKey:@"cardVisual"]];
...
[coreDataStack saveContext];
...
-(NSData*) fileDataForStackFromParseFile:(NSData*)data {

    PFFile *userImageFile = [PFFile fileWithData:data];
    [userImageFile getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
        if (error) {
            NSLog(@"zzbamm! %@",error);
        } else {
            return userImageFile; //the data for saving to stack
        }
    }];
}

I get the error below, at the ^ block sign:

Incompatible block pointer types sending 'PFFile *(^)(NSData *strong, NSError *strong)' to parameter of type 'PFDataResultBlock' (aka 'void (^)(NSData *strong, NSError *strong)')

I think IOS assumes that i try to return something from a void method, in fact that return is for my "fileDataForStackFromParseFile" method.

What seems to be the problem?

I also want to ask if this is a good approach for my purpose or it is completely useless? Any other suggestions?

I'm stuck, your help needed.