Simple example of using a UIActivityController in Swift.
You need to be logged into Facebook and Twitter for the options to share to them shows up. (You can do this in the simulator by going to the settings app)
Two extras:
The UIButton is not necessary. But you can use the UIActivityController like this.
The Popover for iPad is not necessary either. But if you want to do it, this is how.
This project is in the public domain. Not much to it.