As you design your watchOS app, understand the foundations on which Apple Watch itself was designed:
Lightweight interactions. Apple Watch was designed for quick interactions that make the most of the display and its position on the user’s wrist. Information is quick and easy to access and dismiss. The best apps support fast interactions and focus on the content that users care about the most.
Holistic design. Apple Watch was designed to blur the boundaries between device and software. For example, Force Touch and the Digital Crown let users interact seamlessly with onscreen content. Your own apps should enhance the user’s perception that hardware and software are indistinguishable.
Because Apple Watch was designed to be worn, its UI is attuned to the user’s presence. No other Apple device has ever been so closely connected to the user. Be mindful of this connection during the design process.
Designing a great app requires a focused approach. Interactions with Apple Watch are measured in seconds, so your app must quickly provide the user with essential information. Three primary themes define the design approach to take:
Glanceable. Glanceable apps make the most important information readily available to the user. Interactions occur over short periods of time, so apps must convey the most important information up front and communicate that information clearly and without distraction. Being glanceable also means keeping the app’s snapshot up-to-date so that the Dock is always displaying current information. A glanceable app provides a complication to give user information directly from the watch face, and it uses a custom notification interface to maximize the scan-ability of notification content.
Actionable. Actionable apps are mindful of the information they present to the user. An actionable app anticipates the user’s needs by ensuring that what’s onscreen is always current and relevant. It takes advantage of opportunities to update its interface, using background time to fetch new data, update its complication, or refresh its snapshot. It provides a complication, so that users can access the app easily. Its custom notification interfaces include custom actions to handle common tasks without opening the app.
Responsive. Interactions with your app should be quick. A responsive app provides a complication and keeps its snapshot up-to-date. It minimizes the time it takes to launch and load new screens. It responds to user interactions with immediate feedback about what the app is going to do, and then uses notifications to deliver progress updates later.
What's New in watchOS 3
With watchOS 3, you can build more powerful apps than ever.
- The Dock. Accessed with the side button, the Dock holds up to ten of the user’s favorite apps. Apps in the Dock are given an opportunity to run at least once an hour so that they can check for new content. Apps can also update their snapshot, which is the static version of the app’s interface displayed in the Dock. These updates make the Dock a useful way for users to get information quickly.
- Stickiness. The most recently used app remains in the foreground for up to 8 minutes after the user drops their wrist, causing the app to appear (instead of the clock face) when the user next raises their wrist. This makes it easier and faster to perform tasks that occur frequently but intermittently.
- Gesture support. Gesture recognizers make it really easy to add custom tap interactions to your apps, touch interactions such as tap, swipe, and pan. The gyroscope is also accessible in addition to the accelerometer.
- Direct access to the Digital Crown. An app can be notified when the user rotates or stops rotating the Digital Crown, and can retrieve the rotational speed of the Digital Crown while it's in motion. You might use this information to change selections, modify values, or update your interface.
- Improved notification support. You can schedule local notifications directly from your watchOS app, even while your app is running in the background. You can use local notifications to alert users when tasks are complete, giving users the freedom to drop their wrists more quickly rather than wait for your app.
- Extra large complications. An extra large family of complications is available to support several of the new watch faces.
- Workout app improvements. Workout apps continue running in the background for the duration of the workout session. This lets you gather sensor data in real-time, update your app’s interface regularly, and generate local notifications when the user reaches important workout milestones.
- Background App Refresh. Apps can now run in the background to process downloaded content, update their snapshot, and update the app’s state information and interface. Design your app so that users can drop their wrist immediately after finishing a task, while the app finishes that task in the background.
- Faster interactions. Apps that appear in the Dock or whose complications appear on the watch face remain in memory, minimizing the time it takes for them to launch and respond to the user. Built-in apps have been designed with the goal that interactions should take only 2 seconds, and the new features like Background App Refresh make this goal more achievable than ever.
watchOS apps are built using components from WatchKit, a programming framework that defines the available interface elements. This framework lets apps achieve a consistent appearance, while at the same time giving you tools to customize the look of your app. WatchKit elements are adaptable, enabling you to design a single app that looks great on all Apple Watch devices. The interface elements provided by WatchKit fit into two categories:
- Views. Contain the content people see in your app, such as text, images, animations, and video content.
- Controls. Initiate actions and convey information. Buttons, switches, and sliders are examples of controls.
Apps with complications also use components from ClockKit, a programming framework that defines the templates for presenting your complication data on the watch face.