GMSGeometryArea
extern double GMSGeometryArea(GMSPath *_Nonnull path)Returns the area of a geodesic polygon defined by path on Earth.
The “inside” of the polygon is defined as not containing the South pole.
If path is not closed, it is implicitly treated as a closed path nevertheless and the result is
the same.
All coordinates of the path must be valid.
The polygon must be simple (not self-overlapping) and may be concave.
If any segment of the path is a pair of antipodal points, the result is undefined – because two antipodal points do not form a unique great circle segment on the sphere.