Enthusiasts Guide to HomeKit

Apple’s smart home platform has grown in maturity quite rapidly since it’s inception in 2014. There are now many new technologies included, and these have contributed to security, usability, and automation capabilities that have arguably outpaced other major platform efforts.

As with any software product, growing feature sets lead to growing complexity, and it can become harder for users to know how to get things done, or even what those capabilities are. We’ve compiled a library of guides that will delve into these features so you can get the details on the aspects you’re interested in.

We’ll cover some general info up front, but scroll down to the features library if you want to dive right in.


  1. What is HomeKit?

  2. History

  3. How Does it Work?

  4. Main Features

  5. Accessory Types

  6. How-To Index

  7. Conclusion

What is HomeKit?

HomeKit is a smart home automation platform developed and maintained by Apple. HomeKit was created as an answer to the growing problem of smart home fragmentation that was out of control by the mid 2010s.

Every device maker had their own app, and their own automation system, and nothing worked together easily. Some older efforts had attempted to resolve this through proprietary communication protocols such as Z-Wave, Insteon, and Zigbee, but only with limited success.

Apple’s approach was to leverage their already large device footprint to provide a standardized foundation with which smart devices (called Accessories) could be controlled. HomeKit enforced the use of the communication protocols already on their devices, WiFi and Bluetooth, which were both ubiquitous global standards already.

This was coupled with stringent security model and a new application layer called the HomeKit Accessory Protocol (HAP) that provided a clear standard language for all devices to talk to each other. HAP has been open-sourced as part of Apple’s contribution to the new Matter IoT standard.

This approach was similar to Z-Wave and ZigBee in that devices were given classes and attributes to make it clear what commands they could accept, and what data they could provide, but unlike the older competition HAP enforced these details much more rigidly ensuring complete interoperability.

The cost of this approach is that only device capabilities specifically allowed by HAP could be used, which limited the kinds of devices HomeKit users could employ. This has improved over time as Apple has added more classes and attributes, but remains a limitation in some areas.

HomeKit History

2014 - HomeKit Announced with iOS8
2017 - Software based accessory authentication
2017 - Expansion of supported accessory types
2017 - HomePod bring ambient voice control
2018 - Apple joins Thread group
2019 - Siri Shorcuts usable in automations
2019 - HomeKit Secure Video added
2019 - HomeKit Secure Routers added
2020 - Thread protocol support arrives with HomePod Mini
2020 - Apple joins Connected Home over IP consortium
2021 - Home Key and local Siri processing added

In addition to these major events, automation capabilities and user interface improvements have trickled out with each major iOS version. These include features like an auto-off timer for automations, the ability to set conditions for when triggers should happen, more controls over notifications, and improvements to how accessories can be controlled and displayed in the Home app.

How HomeKit Works

At it’s most basic level, HomeKit uses an Apple device, typically an iPhone as the basis of a HomeKit ‘Home’. Each Home is securely linked to a specific Apple ID and the configuration data for the home is encrypted and synchronized to iCloud.

Any Apple device logged in to the Apple ID is able to synchronize the Home data which provides IDs and security keys for each Accessory. That device can then send commands to those Accessories via the HAP. This creates a decentralized smart home in that any logged in user device will have control and visibility of the smart home, iCloud only provides a means to sync changes between devices and doesn’t act as a controlling hub.

This also means HomeKit provides complete local control and does not require an internet connection in order to receive status updates from accessories or send commands to them.

While the use of only end-user devices for control does work, it significantly limits HomeKit’s capabilities. This is because the device must be on the same network as the accessories in order to communicate, and many automated features can’t function. To get around this, certain Apple devices can act as a hub. These are devices that are always online and connected to the local network such as Apple TV and HomePod.

Having such a hub allows for automated rules to trigger reliably, video cameras to be able to record, and remote access to the smart home via iCloud with the hub acting as a secure gateway. The hub still retains local control and everything will function normally during an internet outage, apart from remote access.

Additional Apple IDs can be invited to the HomeKit Home, and this allows them to be given their own secure key to synchronize the home data from iCloud. Such additional users will have full control of Accessories, with the ability to limit their access to cameras, remote access and changes to the home configuration.

HomeKit device communications

HomeKit device communications

HomeKit Features

HomeKit Automation Features

The automation rules that can be created in the official Home app afford a good base for many smart homes but fall short in allowing truly smart automation. HomeKit actually offers a lot more than the Home app exposes, and this guide goes into how to get the most out of your automation journey.

HomeKit Home Hubs

Home hubs are officially option, but in any serious HomeKit home they are essential. This guide goes into what they do, why, and how to set one up.

HomeKit Secure Routers

IoT devices are notoriously prone to being hacked or allowing unwanted access to your home network. While HomeKit mandates end to end encryption and authentication, this feature goes further by enabling tight firewall control over what your accessories can access inside and outside your network.

HomeKit Secure Video

Smart security cameras are an easy and convenient way to get oversight of what’s going on at home, but they often use third party clouds to record video with no way to know if those videos are secure. This feature ensures all your videos are processed and encrypted locally before they ever leave your network.

Home Key

A convenience feature that works with compatible smart locks to enable quick unlocking by simply tapping your iPhone to the lock. This uses the iPhone’s NFC feature and works similarly to using Apple Pay in a store. Home Key improves the speed and reliability of using smart locks by dispensing with the slower Bluetooth methods used by most existing products.

Siri Configuration Options

There are now more options to configure how Siri sounds and how it interprets what you say. This guide covers the options available and the steps to use them correctly.

Voice control using Siri

Understand the various naming contexts in HomeKit and how you can best use them to make Siri voice control clear and effective.

Extending HomeKit beyond official accessories

Official HomeKit accessories are often best in class, but also expensive. This is due to the need for Apple certification on both counts. Sometimes we just want to use something we already have, or we need a product that no one has bothered to certify for HomeKit yet. This guide shows you how to create an interface for many non-HomeKit devices.

HomeKit Groups and Zones

See how these two different abstract groupings allow you to customize your HomeKit voice command experience. These features provide a great deal of flexibility in configuring your smart home so that you can control logical groups of devices with a single command when necessary.

Accessory Types

HomeKit now supports a much wider array of device types, with the more recent additions being Thermostats, Routers, TVs, Cameras, Faucets, and Sprinklers.

Each accessory type includes the ability to use a variety of attributes to determine the data that accessory can show. While this is more focused around sensors it is also important for device state information. For example, Thermostats can show the current and target temperature, whether it’s heating, cooling, or off, and may include humidity sensors as well.

The controls that are available are also determined by class, but not all controls need to be available on a given accessory. Following the Air Conditioner example you will have a temperature control, but you may optionally have one for fan speed, and oscillation.

The accessory classes currently supported are:


Frequently Asked Questions

What can I do with HomeKit?

HomeKit allows you to control smart devices with your smartphone, through your Apple TV, with Siri voice commands, and to set up automation rules that allow your smart devices to react intelligently to what’s going on in the home. You can also use HomeKit to keep an eye on a wide variety of home status information, depending on the accessories you have. This includes things like viewing camera feeds, seeing the temperature, humidity and air quality in various rooms, checking if doors or windows are open, and seeing if any motion has been detected in different areas, to name a few.

Do HomeKit devices need to be on the same Network?

For HomeKit to work all hubs and accessories need to be on the same home network. If you have a Home Hub your client apps will be able to control the home and check on status data from anywhere with an internet connection, and you’ll get any notifications you’ve configured as well.

What is the best way to use HomeKit?

The best way to use of HomeKit is with a Home Hub. This can be a HomePod or an Apple TV device. iPads are supported too but are not recommended as the primary hub, and this support will likely go away now that the HomePod Mini provides a much more cost-effective alternative.

What apps work with HomeKit?

HomeKit uses a publicly available API which allows app developers to access most HomeKit functions. The official Apple Home app, along with a range of third-party apps such as Controller, Home+, Eve, and HomeDash can be used as clients to control your smart home. There are also many other third-party apps with more specific focuses that can utilize HomeKit data.

Does HomeKit work when the internet is down?

HomeKit sends commands from your iPhone or a Home Hub directly to the target smart devices over the local network, so it will continue to work normally when the internet is down. The only things you lose are Siri voice commands (which need Apple’s servers), and remote access.

How does HomeKit know when I am home?

HomeKit uses the geolocation of each member of the home as determined by their personal devices, either an iPhone or Apple Watch, to know who is at home. ‘Home’ is considered being within a fixed distance of the home’s specified address in the Home app. The distance is not configurable and is about 100ft/30m.


If you’re looking for a smart home platform that offers local control, capable automation rules, strong security and privacy protections, and ease of use, it’s hard to go past HomeKit. The key blocker for some will be the need to embed yourself in Apple’s device ecosystem as HomeKit only runs on Apple devices and requires iCloud for configuration management.

HomeKit is tightly integrated into that ecosystem, which is a real benefit for Apple users, and makes it even more compelling to adopt it as your main smart home platform. The cost of accessories can be high to ensure quality and security, however, cheaper devices can be easily integrated by those willing to go a little further down the rabbit hole.

Apple is continuing to focus on HomeKit development, with more new hires being sought for the team. That’s encouraging for the future of the platform and Apple’s commitment to see it grow.