HKWorkoutSession: Not getting Heart Rate when screen is turned off in watchOS 2

Question

I am using iOS 9 beta 4 and watchOS 2 beta 4.

I can't seem to get any heart rate data when the watch screen turns black (locks). I will get a call to applicationWillResignActive and then the heart rate data just stops.

It seems that the sensor is deactivating after some time as well (not green anymore), when the screen locks.

Anyone else seeing this behavior? I can post my code for initing the WorkoutSession if anyone else getting heart rate data when the screen on the watch is locked.

Answer 1

Starting in watchOS 3.0 you can add the WKBackgroundModes entry with the workout-processingvalue to the extension's Info.plist.

From the docs:

Running in the Background Workout sessions can run in the background. Background running grants an app the following abilities:

The app continues to run throughout the entire workout session, even when the user lowers their wrist or interacts with a different app. When the user raises their wrist, the app reappears, letting the user quickly and easily check their current progress and performance.

The app can continue to access data from Apple Watch’s sensors in the background, letting you keep the app up to date at all times. For example, a running app can continue to track the user’s heart rate, ensuring that the most recent heart rate data is displayed whenever the user raises their wrist.