Heading(setHeading)
Set ‘heading’ to rotate the map in the desired direction.At this point, the compass shape also looks at the set value.
For example, a 90° compass loos west.You can set 0~360. The default is 0 degrees(North)

mapInstance.setHeading(value);

Heading(getHeading)
Gets the value of the set map direction.

mapInstance.getHeading()

Return : getHeading
The direction of the current map.

[ example : getHeading ] 
mapInstance.getHeading()
return : 90