Xcode's built in "Copy Files Build Phase" is the normal way to copy files to a product. Is there any reason you're not using it?
You can add additional copy phases from the "Editor" -> "Add Build Phase" menu, if needed.
If the files are all contained in a folder but shouldn't be added manually to the Xcode project, you can use a folder reference (the blue folders in the project navigator).
The advantage of this build phase is that it uses Xcode's dependency tracking, so it does not copy files that have not changed.