5 hidden details in WatchKit

There are only a few months left before the official release of Apple Watch, but there are still many things we don’t know about this product, such as price and battery life. This morning, Apple officially released WatchKit. Through in-depth digging in the WatchKit Programming Guide and the Apple Watch Human-Computer Interaction Guide, we found several details that Apple did not mention in the keynote speech, such as the use of new fonts for a better experience on small-size displays.

Here are five details hidden in the WatchKit SDK:

1. There are two resolutions

The screen resolution of the 38mm Apple Watch is 272x340 px, and the resolution of the 42mm is 312x390 px. Although Apple claims that both are Retina displays, developers still need to prepare to support UI elements of both sizes.

2. Developers need to prepare a square app icon

There are a lot of prototype icons placed on the Apple Watch home screen, but Apple tells developers in the guide to prepare square icon images. The system automatically applies a circular mask. When the Apple Watch app functions like an iOS app, its icon will be visually consistent. But when the Apple Watch app is a complete application or controller, the icon will be different.

3. Apple Watch did not support fully native third-party apps when it was first released

In the early days of Apple Watch, you don't have to worry about apps eating up your memory and consuming power, because the system will not let the app run on the local machine, but will hand over the processing tasks to the iPhone. When the app is launched on the Apple Watch, the WatchKit extension on the iPhone will run in the background to update the UI and respond to user interactions.

4. Two interface types

When Apple Watch was first released, there were only two types of app layouts available: Hierarchical, similar to the Mail app, and Page Based, similar to the Weather app. In Hierarchical apps, users have to browse through each screen until they find what they want. Page Based apps require users to swipe horizontally.

5. The system font is the same as the font used by Macintosh computers

The Apple Watch system font is called "San Francisco". It is the first generation of bitmap fonts for Macintosh, mainly to improve the readability of content on small screens.

6. Apple Watch has its own icon grid system

Developers still need to prepare square app icons, but they need to create 8 different variations to support both screen sizes.