Many files in SBSearch*, SPUISearch*
How to open:
[[%c(SpringBoard) sharedApplication] _revealSpotlight];
This will open Spotlight from anywhere. If you are inside an application, it will close that application and go to the homepage in order to open Spotlight.
[(AXSpringBoardServer *)[%c(AXSpringBoardServer) server] revealSpotlight];
How to dismiss:
[[%c(SBSearchGesture) sharedInstance] resetAnimated:YES];
If you are interested in creating your own search results check out SearchLoader.