HomeKit is a new framework for communicating with and controlling connected devices in a user’s home using iOS Apps. Apps can enable users to discover devices in their home and configure them, or you can create actions to control those devices. Users can group actions together and trigger them using Siri.
Home Kit provides seamless integration between accessories that support Apple's Home Automation Protocol and iOS devices, allowing for new advances in home automation. By promoting a common protocol for home automation devices and making a public API available for configuring and communicating with those devices, Home Kit makes possible a marketplace where the app a user controls their home with doesn’t have to be created by the vendor who made their home automation accessories, and where home automation accessories from multiple vendors can all be integrated into a single coherent whole without those vendors having to coordinate directly with each other.
Home Kit allows third-party apps to perform three major functions:
Discover accessories and add them to a persistent, cross-device home configuration database.
Display, edit, and act upon the data in the home configuration database.
Communicate with configured accessories and services to get them to perform actions, such as turning on the lights in the living room.
The home configuration database is not only available to third-party apps, it’s also available to Siri. This allows users to give commands like, “Siri, turn on the lights in the living room.” If a user creates a home configuration with logical groupings of accessories, services, and commands, Siri can make it very easy to accomplish sophisticated operations with voice control.
For more info: see the documentation here
