In general, for iOS, apps can request true north or magnetic north heading from the system, however, they might only get magnetic north back if the, user has particular device settings (e.g. compass calibration turned off), so the app developer has to deal with that.
My app in particular will request true heading from iOS, it will check what it got and if magnetic north was returned instead, the magnetic declination will be calculated for your location using the latest World Magnetic Model and applied.
There's also a display of your magnetic declination in the bubble level / compass tool.
tldr: Polar Scope Align will always use true north (magnetic declination included in the calculation), for other apps it would depend on the particular app.
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Originally Posted by RugbyRene
One more question. Do the compass/polar align tools take into account magnetic declination or do I need to adjust my heading?
Rene
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