In iOS 10, Apple has announced an API for Siri called SiriKit. However, you can only do it as an app extension and only if your app implements one of the following types of services:
- Audio or video calling
- Messaging
- Payments
- Searching photos
- Workouts
- Ride booking
- Climate and radio
SiriKit is a way for you to make your content available through Siri.
It also lets you add support for your services to the Maps app. To
support SiriKit, you use the Intents framework and Intents UI
framework to implement one or more extensions that you then include
inside your iOS app. When the user requests specific types of services
through Siri or Maps, the system uses your extensions to provide those
services.
This means SiriKit cannot be used for the scenario mentioned in the question and in ways that many of us would like.
Source: Apple Docs for SiriKit