10 Interesting things WatchKit revealed about the Apple Watch

image WatchKit features

Apple released the WatchKit SDK for Apple Watch to developers yesterday, and since then, a lot of new information has come out about its software and hardware.

We already reported that the two sizes of the Apple Watch would support two different resolutions, but there’s a lot more that the SDK revealed. Here are some key points about the Apple Watch that Apple didn’t reveal during the keynote:


As pointed out yesterday, the 42 mm version of the Apple Watch has a resolution of 312 x 390 pixels while the smaller 38 mm version has a resolution of 272 x 340 pixels. Both these displays run at 2x, that is, Retina mode and sport a 4:5 aspect ratio.

apple watch resolutions

iPhone Required

The Apple Watch requires the iPhone at all times, and the code of a Watch app actually runs in the background on an iPhone, which communicates with the device:

“As the wearer interacts with the Watch App, Apple Watch and iPhone pass information back and forth. Taps and other messages from Apple Watch cause code in your WatchKit Extension [e.g. iPhone] to execute.”

A developer needs to have an iPhone app in order to make an Apple Watch app. The app has two components — one is the interface skeleton that lives on the Apple Watch, and the other is the actual code that drives this skeleton, which runs on the iPhone. This scheme prevents huge battery drains on the Apple Watch, and also ensures that the processing power is no longer dependent on the Apple Watch, but on your iPhone.

Native Apps coming in 2015

In the announcement, Apple says that fully native Apple Watch apps will be coming next year:

“Starting later next year, developers will be able to create fully native apps for Apple Watch.”

The native apps will have the ability to run without an iPhone.

Existing Capabilities and Types of apps

For now, developers can create Glances, Actionable Notifications and WatchKit apps.

Glances are a template-based notification, and are not actionable in any real capacity by the user. However, Glances can link directly to the parent application on the iPhone. For instance, a Glance can show the weather of an app, but if the user wants to learn anything more, they’ll need to activate the full weather app on their iPhone.


Actionable Notifications are areas that cannot be customized, insofar that they are simply the same notifications that users currently see on their iPhones now. Developers can, though, include a customized image or graphics to accompany the incoming notification.


WatchKit Apps give developers a little more freedom than glances or Actionable Notifications, but they’re still restricted to the default set of control and UI elements on the Apple Watch:

WatchKit apps have two parts: A WatchKit extension that runs on iPhone and a set of user interface resources that are installed on Apple Watch. When your app is launched on Apple Watch, the WatchKit extension on iPhone runs in the background to update the user interface and respond to user interactions.

More Sizes

On the iPhone, developers have control over the positioning of the various elements on the screen. On the Watch however, the system dictates the arrangement of the UI elements. Apple says that the system places elements “downward from the top left corner of the screen, filling the available space.” While this system may be limiting for developers, it gives Apple more freedom to add any watch size in the future, and the app lays out based on the screen size without any effort required from the developer’s end.

Two Types of Notifications

The Notifications that appear on the Apple Watch can be a “Short Look” or “Long Look” notification. A Short Look notification appears when the user just raises their wrist, and a Long Look notification appears if the user continues to keep their wrist raised for a long enough time.

short look long look apple watch notification

Left: Short Look, Right: Long Look

No Custom Gestures

Apple doesn’t allow developers to add custom gestures in Watch apps like on the iPhone. Instead, interactions like vertical, horizontal and edge swipes, and taps are handled by the system. Just like on the iPhone, a swipe from the left edge takes you back one screen. There are no multi-finger gestures like pinch, presumably because the screen on the Watch is quite small.

Force Touch

To compensate for the lack of gestures, the Apple Watch has an input method called Force Touch, that displays a context menu for the current screen. Force Touch is powered by the Apple Watch’s ability to detect pressure, along with touch.

Series of Images for animations

Rather than supporting animations through code, Apple asks developers to provide a series of images of their pre-rendered animation, that will play on the Apple Watch. Developers can cache up to 20 MB of images on the Watch, and everything else comes from the iPhone.

Install Flow

Since a Watch app comes bundled with the iPhone app, during an app installation, the system prompts the user to install the Apple Watch app, if a watch is paired.

[via The Verge]