I am developing an app for iOS and watchOS to collect SPO2 levels at a certain frequency while in sleep. I have gone through all the documents I couldn't find any API to trigger the oximeter programmatically.
SPO2 level measurement
That’s correct. You should be able to read values from HealthKit, tho.
I can read from the health kit but how can I set the oximeter to start measurement at a certain time? Then only I can collect the data from HealthKit.
It's not possible to trigger a reading via API. Please file a feedack at feedback.apple.com with your use case.
Did you ever found a way to trigger a SPO2 reading ?