From D&D Wiki
|This material is published under the OGL 1.0a.|
A swift action consumes a very small amount of time, but represents a larger expenditure of effort and energy than a free action. You can perform one swift action per turn without affecting your ability to perform other actions. In that regard, a swift action is like a free action. However, you can perform only a single swift action per turn, regardless of what other actions you take. You can take a swift action any time you would normally be allowed to take a free action. Swift actions usually involve psionics or the activation of psionic items; many characters (especially those who don’t use psionics) never have an opportunity to take a swift action.
Manifesting a quickened power is a swift action. In addition, manifesting any power with a casting time of 1 swift action is a swift action.
Manifesting a power with a manifesting time of 1 swift action does not provoke attacks of opportunity.