If I allow an application to write data to iOS Health, e.g. a number of steps; would it corrupt the existing tracking made by the phone itself? In other words:

  • iphone is tracking the number of steps and writes data to iOS Health
  • app is tracking the number of steps and writes data to iOS Health

Would that double the value of the steps counter? What's the purpose of allowing apps to write the same data as iPhone is already tracking?

1 Answer 1


Apps can write data to Health because this allows you to add data from other sources.

For example, you might go on a run without your iPhone but with another health tracker which could track the activity (such as steps). The linked app for this tracker could import the data into the Health app.

iOS Health will figure out duplicate data by itself and won't count activities twice.

  • Thanx. So if I only use iphone without any additional gadgets, there is no need to turn this 'write' permissions, right?
    – ɹoƃı
    Oct 25, 2017 at 12:49
  • @ɹoƃı Which write permissions are you referring to?
    – grg
    Oct 25, 2017 at 18:16
  • the app is asking if it can write data to Health for steps counting.
    – ɹoƃı
    Oct 25, 2017 at 21:55

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