Developing Next-Generation Apps for the Apple Watch

The word is out! The new Apple Watch is coming your way in early 2015, providing a brand new platform and great opportunities for a new category of apps. In this post I'll cover some of the basic features available for app developers so you can begin thinking about how these features can be put to use in your own custom apps.

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As you might expect, Apple announced a new framework called WatchKit that allows you to create apps for the Apple Watch. Unfortunately, Apple didn't release the WatchKit framework in the latest September 9, 2014 update of Xcode 6, but as soon as it becomes available, I'll dive in and start writing articles about it.

So far, we know that WatchKit allows you to create custom apps as well as notifications that users can interact with.

New Ways of Interfacing with Users

A brand new category of device requires a brand new way of allowing users to interact with that device. As usual Apple's designers have done an outstanding job.

The digital crown (Figure 1) is a new input and navigation device containing infrared LEDs that translate rotary movement to digital data. You can rotate the digital crown to zoom in and out of apps and their content. You can also use it to allow users to select between different options in your apps. When you press on the digital crown, it acts as the Home button, a familiar gesture for iOS users. As Apple mentioned in the keynote, the beauty of the digital crown is that you can interact with it without blocking the screen.

Digital crown
Figure 1 - The digital crown

There is a button directly below the digital crown that you can press to bring up a list of friends that you can contact quickly (Figure 2). 

Friends button
Figure 2 - The button below the digital crown displays a list of friends.

The surface of the watch is a flexible Retina display that is comprised of a single crystal of sapphire (touted as the second hardest transparent material after diamond.) This display goes beyond the capabilities of other iOS devices. Not only does it sense touch, it also senses force—the user pressing down, as depicted in Figure 3. This allows the display to recognize the difference between a tap and a press, which provides a new type of input gesture—a necessity for such a small touch surface.

Sensing Force
Figure 4 - The Apple Watch surface can detect the user pressing down.

The back of the Apple Watch also acts as another input device. It has four sapphire lenses, infrared and visible light LEDs along with photo-sensors that can detect your heart rate (Figure 5).

Back of the watch
Figure 5 - The back of the watch has has four sapphire lenses that can be used to detect your heart rate.

Other input devices include a gyroscope and accelerometer that can be used in conjunction with the GPS and WiFi from your iPhone to provide detailed information about your physical movements. They are also used to sense when you are raising your wrist so that the Apple Watch automatically activates the display.

Output Devices

In addition to the flexible Retina display, the Apple Watch includes other output devices that allow you to interact with users. 

First of all, the watch has water-resistant speakers (thank you, Apple) that allow you to interact with the user by playing sounds or music. 

The Apple Watch also has a linear actuator that provides tactic feedback in the form of gently tapping the user on the wrist. To give you a sense of how nuanced these taps can be, the Maps app uses different wrist taps to indicate turning left versus turning right.

Types of Apps

To help jump start your imagination with ideas of the kinds of things you can do with Apple Watch apps, consider some of the apps that were mentioned during the Apple Event:

  • American Airlines allows you to handle the entire process of checking in to boarding the plane with their app.
  • Starwood hotels allows you to check in on your watch and you can open your hotel door by waving your watch in front of the door.
  • The City Mapper app gives you mass transit directions and reminds you to get off at the right stop by tapping on your wrist!
  • The Pinterest app alerts you when you are near sites of interest that you have marked in advance and even gives you walking directions.
  • BMW lets you see the charge level of your car, and will give you directions to where you parked your car.
  • Major League Baseball lets you see the current sports scores.
  • Honeywell lets you control the temperature in your home.
  • The Lutron app allows you to control the lighting in your home.
  • The Nike app allows you to challenge your friends to go for a run.

How Can You Get Ready Now?

If you have apps that you have written for iOS devices, and you want to create a version of your app for the Apple Watch, I recommend taking a good look at your app to make sure that your core logic isn't embedded in the user interface. The UI you would create for an Apple Watch app is very different than that of an iOS app, so you will create a brand new UI experience. If you keep your core logic separate from the UI, you can easily move functionality to the new Apple Watch platform. For more information on creating this type of flexible app architecture, check out my blog post on App Architecture.


Personally, I'm excited to get my hands on WatchKit and begin building the next generation of apps. Writing for a brand new platform provides an unparalleled opportunity to get your apps noticed when there are only a handful of apps to choose from.
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Kevin McNeish is author of the new book “Learn to Code in Swift” as well as the “iOS App Development for Non-Programmers” book series (, winner of the Publishing Innovation Award. Kevin is also an award-winning app developer, software architect, and conference speaker in the U.S. and abroad. He has spent much of his career making difficult concepts easy to understand. Follow Kevin on Twitter: @kjmcneish.