A Developer's Perspective on the Apple Watch

Reinventing App Development

Programming for the watch actually requires creating two apps at once, because the Apple Watch doesn't work independently. There is a master-slave relationship between an iPhone and an Apple Watch that is linked to it. Functionality for both components is included in a single iOS app; when the app (called a watchkit extension) is deployed on the phone, it asks users to install the corresponding watchkit app on the linked watch.

The "watch" part of the app is in many ways simply an interface device for the app on the phone. As Apple's CEO Tim Cook told Fast Company, the small size of the watch screen means reinventing user interactions. Besides the usual gestures, the watch includes new technology, including a screen which is sensitive to touch pressure, not just touch.

The watchkit app contains the storyboard and resources needed to display the user interface. The watchapp extension on the iPhone does the processing and notifies the watchkit app of changes to the user interface.

There are two kinds of notifications that can be used. Glances are read-only views intended to present essential information—similar to glancing quickly at your wrist to check the time. Notifications on the Apple Watch are similar to notifications on the iPhone. These notification messages can let the user take action by clicking on a button.

Support for Developers

The first set of Apple Watch apps were developed internally, but the development kit is being made available to developers. Apple's provided a significant amount of resources to encourage app development, including a programming guide which explains how development for the watch works as well as how to leverage iOS techniques.

Apple has also developed Human Interface Guidelines to help developers make the best use of the new interface functionality. Recommendations cover when to use a hierarchical navigation style versus a page-based navigation style and when to choose each of the four interaction methods (taps, gestures, force touch, and the digital crown).

Killer Apps

Because the Apple Watch is new technology, companies are in search of the killer app for the device. Amazon has already announced it will create an app for the watch. Several airlines will create apps to notify travelers of information such as gate changes. A planned app from Rolocule may turn the watch into a Wii controller—if the SDK provides the needed functionality.

The New York Times expressed some doubt about whether the public wants devices like the Apple Watch. Of course, most consumers didn't have smartphones until Apple came out with the iPhone. Today, it's hard to get through the day without using a smartphone. Apple's given us a unique platform; it's up to developers to make it something that end users feel they need.