HealthKit data store on the Apple Watch without iPhone?

Question

Is it possible to read and write HealthKit data without an iPhone in range? In other words, does the HealthKit data reside in the iPhone only, or is it in the cloud and syncs across devices?

I would like to make an Apple Watch / watchOS 2 app that reads heart rate, but without requiring to having your iPhone reachable. Is this possible?

Answer 1

Reading heart rate samples from HealthKit on the watch does not require the paired iPhone to be nearby. HealthKit data generated or saved on Apple Watch is cached locally and will sync back to the user's phone later on.