Dev:SearchBundles

Search bundles are bundles to provide search results for Spotlight. There is a hardcoded limit of 11 (for iOS 8 and below, unknown for iOS 9) search bundles (domains), all of which are occupied by built-in ones.

SearchLoader is a developer library for adding more search bundles.

Finding a Search Domain
will list all the domains

will then give you their bundle ids

Categories
In iOS 9, search have a combination of categories, bundle id, domains, and display identifiers. For example, Top hits has a category of com.apple.spotlight.tophits domain of 0 and display identifier of DOMAIN_TOPHIT

Structure of a Search Bundle
Search bundles should have an extension of .searchBundle. The principle class should conform to the SPSearchDatastore protocol.