Recently I encount a nice method name from Bitwaker post, it look like this:

	float angleFromNorth(CGPoint p1, CGPoint p2)

and method implementation is like this:

	float angleFromNorth(CGPoint p1, CGPoint p2) {
		float vx = p2.x - p1.x;
		float vy = p2.y - p1.y;
		double radians = atan2(vy, vx);
		angle = 180.0 * radians / M_PI;
		return angle;
}

The reason I love this name is:

Using fromNorth states clearly Y-axis’s oriention is upward.