Core Motion altitude vs Core Location altitude

Discussion in 'iOS Programming' started by moonman239, Sep 23, 2014.

  1. moonman239 macrumors 68000

    Mar 27, 2009
    I'm building an app that will calculate the sea-level pressure at the user's current location. I use Core Motion to get the current barometric pressure reading, and Core Location to get the user's current altitude.

    Does the Core Motion altitude calculation account for weather changes? If so, does it get its sea level pressure data from online?
  2. TheWatchfulOne macrumors 6502


    Jun 19, 2009
    You probably figured this out already, but Core Motion Altitude is relative and Core Location Altitude us absolute.

    Meaning, CMAltitude tells you your relative altitude at your current location compared with your previous location.

    CLAltitude gives you your distance above sea level at your current location.

    I haven't seen anything in the docs yet about barometric pressure readings although I thought I heard something in the keynote about the new iPhone having a barometer. Did I imagine that? Or maybe I'm confusing it with a rumor I heard?
  3. PhoneyDeveloper macrumors 68040


    Sep 2, 2008

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