To further expand on Apple's recommendation to not make Swift libraries just yet — It's also an matter of compatibility. You could certainly make a Swift framework, but given that Swift as a language is changing every 6 months or so right now, it doesn't make sense to make a framework using Swift.
You could easily hold up another project if you haven't changed your Swift code to the latest, or the opposite is true as well: Your Swift framework is up-to-date with the latest language, but the app using your framework is not, etc.
You could easily hold up another project if you haven't changed your Swift code to the latest, or the opposite is true as well: Your Swift framework is up-to-date with the latest language, but the app using your framework is not, etc.