Last year, Apple released Search API. *https://developer.apple.com/videos/play/wwdc2015-709/
Before this, it was impossible to get the list of installed apps on iOS.(is it right?)
If I use this Search API, can I get the list of installed apps on iOS? Anyone tried that?
No, the search API won't allow you to get a list of installed apps. Also, it is highly unlikely that this capability will be provided by Apple anytime soon.
Apple takes user privacy very seriously, so going by this philosophy - it makes sense that an app won't have access to this kind of information, not without an explicit permission anyway.
The various search APIs basically give you the ability to make your own app appear in search results rather than perform a search yourself.