With systemwide improvements in watchOS 4, your apps will be faster and more responsive than ever. Use new background modes for navigation and audio recording. Access Core Bluetooth to connect directly with accessories. And with Apple Watch Series 3, your apps can take advantage of built-in cellular and altimeter capabilities.
With cellular, your apps can connect everywhere and anytime, even when not connected to an iPhone or Wi-Fi. Health and fitness apps can also take advantage of the barometric altimeter to display altitude changes and get improved accuracy for workout metrics from HealthKit.
A single process runs your app’s UI elements and code, decreasing latency and making your app faster and more responsive without the need to change your code. Create an even better user experience with UI improvements, including support for full screen apps and overlapping layers that let your apps show text over video animations. Users can now give your apps permission for location usage right on Apple Watch. And the new autorotate feature lets users easily show content on Apple Watch to another person — great for apps related to payments, language translation, and accessibility.
Access to Core Bluetooth on Apple Watch lets your apps bypass the phone and connect directly with the Bluetooth in Apple Watch, so information is updated instantly and can be seen as soon as users raise their wrists. This feature is useful for a variety of apps, including continuous glucose monitors, surfing apps connected to surfboards with embedded sensors, and sports apps connected to tennis rackets or baseball bats with embedded swing analyzers. Information is sent directly to Apple Watch so users can immediately make adjustments.*
In addition to workout apps, a variety of other apps now have the ability to run in the background. Your turn-by-turn navigation apps can now appear every time users raise their wrist to see the next step in the directions. Apps for navigation, public transit, and tour guides can even send haptics so the user knows when to raise their wrist for timely information. Your audio recording apps can offer continuous voice memos, and you can create a custom UI when recording for real-time feedback.
Use APIs to integrate Siri’s natural language experience into your watchOS apps. SiriKit supports apps for fitness, payments, rides, and messages so users can ask Siri to start a workout, send money, book a ride, and more. And now with watchOS 4, SiriKit is available for apps that are used to take notes. Users can ask Siri to add, change, or delete notes in any note-taking app.
Workout apps can keep running in the background during a workout. Every time users raise their wrist, they’ll see up-to-date metrics and live animations. Fitness apps can also access real-time heart rate data, the gyroscope, route map data, the all-day accelerometer, and enable Water Lock mode, allowing you to create compelling fitness experiences.
Take advantage of rich graphics and media tools in your apps by including support for speaker audio, in-line video, SpriteKit, SceneKit, Game Center for turn-by-turn gaming, and CloudKit for data storage across devices.