iphone - CLLocation - Find magnetic declination / deviation at another location -


i know how find true heading/magnetic heading location phone at, possible find magnetic deviation/declination remote location?

what able drop pin @ place on map , find both true bearing , bearing magnetic variance point.

thanks!

have solved it? otherwise can calculate azimuth angle of remote location. firstly magnetic north heading , true north heading. subtract 2 magnetic deviation.

here how calculate azimuth angle remote location:

-(float)azimuthfromlocations:(cllocationcoordinate2d)first tocoordinate:(cllocationcoordinate2d)second{ float longitudedifference = second.longitude - first.longitude; float latitudedifference = second.latitude  - first.latitude; float possibleazimuth = (m_pi * .5f) - atan(latitudedifference / longitudedifference);  if (longitudedifference > 0)     return possibleazimuth; else if (longitudedifference < 0)     return possibleazimuth + m_pi; else if (latitudedifference < 0)     return m_pi;  return 0.0f; }

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