From iPhone Development Wiki

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.

Search Modes

Value Meaning Displays SearchModel
0 pull left Siri Suggestions, Nearby, News Full
1 pull down Siri Suggestions Partial
2 searching * General/shared?

Each search mode has a different SPUISearchModel. The sharedInstance of SPUISearchViewController currentSearchModel: points to the sharedFullZWKInstance (more research required).