Apple's new WatchKit SDK hints at the future of Apple Watch's apps

Apple released a bevy of developer resources for the upcoming Apple Watch Tuesday.
The company released a WatchKit, documentation and guidelines for developers alongside the new iOS 8.2 SDK. The WatchKit page includes a Getting Started with WatchKit video outlining the new tools and how developers can build apps.

See also: Apple Watch Hands-On: Plenty of Promise, Plenty of Unknowns

The resources also let registered developers download a new font (called "San Francisco" for Apple Watch development), along with PSD templates for designers to develop mockups of their applications.
You need to be a registered developer to download the tools, but anyone can read the Apple Watch Human Interface Guidelines, which outline the basics for designing for the Apple Watch.

The Human Interface Guidelines highlight how notifications works, various layout options and how color animations should be handled.
It's notable that the two different sizes of the Apple Watch (38mm and 42mm) have different resolutions, which results in different pixel sizes for on-screen elements and typography. Just as developers need to design for the different resolutions of the iPhone 4S, iPhone 5, iPhone 6 and iPhone 6 Plus, they also need to take the size differences of the two Apple Watch devices into account.
Apple says that developers can use the same image resources as long as it looks good on both screen sizes. If it doesn't, developers will need to provide separate image resources for each one.

Glances and notifications

Looking through the guidelines, it's easy to get an idea of what applications Apple has envisioned for the Apple Watch. Content should be glanceable and notifications should make sense. Apple even has a term for for glanceable information on Apple Watch apps: Glances.
Although Glances are optional, Apple has rules about how they can be designed. They are template based, and importantly not scrollable. They are also read-only.
When it comes to notifications, Apple has designated two types:

• Short Look Notifications: These are designed to let the user know that an app received a notification and it is displayed only briefly.



Image: Apple

• Custom Long Look Notifications: These provide more detail about an incoming notification and let users interact with app-defined actions.

Image: Apple

Think widgets for your wrist

Image: Mashable composite, Apple

Looking through the documentation, right now it appears that much of the framework for the WatchKit SDK is similar to the Notification Center widgets available for iOS 8. That makes sense because notifications and configurable widgets are two concepts that feel at home on a wrist. For now, it's clear that Apple wants to help users find out about the weather and maybe turn on a nearby heater — not draft a document.
The documentation also makes mention of other Apple technologies such as Handoff and Continuity, which makes sense because these are also areas where a watch app could come in handy.
We'll spend more time looking into the WatchKit SDK and the design resources as time progresses.