How to convert existing non-document Core Data store to uimanageddocument?

Question

How to import data from existing non-document Core Data store to uimanageddocument?

The question is how to copy from the old managedObjectContext to the new one.

Answer 1

The answer is to subclass UIManagedDocument, in which import(simply copy)existing store to the document store:

- (BOOL)configurePersistentStoreCoordinatorForURL:(NSURL *)storeURL ofType:(NSString *)fileType modelConfiguration:(NSString *)configuration storeOptions:(NSDictionary *)storeOptions error:(NSError **)error
{
    // If legacy store exists, copy it to the new location
    NSURL *legacyPersistentStoreURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Guides.sqlite"];

    NSFileManager* fileManager = [NSFileManager defaultManager];
    if ([fileManager fileExistsAtPath:legacyPersistentStoreURL.path])
    {
        NSLog(@"Old db exists");

        NSError* thisError = nil;
        [fileManager replaceItemAtURL:storeURL withItemAtURL:legacyPersistentStoreURL backupItemName:nil options:NSFileManagerItemReplacementUsingNewMetadataOnly resultingItemURL:nil error:&thisError];
        NSLog([thisError localizedDescription]);
    }

    return [super configurePersistentStoreCoordinatorForURL:storeURL ofType:fileType modelConfiguration:configuration storeOptions:storeOptions error:error];
}