Now in beta 4, they've added access modifiers to Swift.
from Xcode 6 beta 4 realese notes:
Swift access control has three access levels:
privateentities can only be accessed from within the source file where they are defined.internalentities can be accessed anywhere within the target where they are defined.publicentities can be accessed from anywhere within the target and from any other context that imports the current target’s module.
By default, most entities in a source file have internal access. This allows application developers to largely ignore access control while allowing framework developers full control over a framework's API.