How to create a Virtual Compass in iPhone app.

#define RadiansTodegrees(Y) ( 180.0* Y / 3.14)

IBOutlet UIImageView *arrow;

IBOutlet UIImageView *Compass;

CGPoint theEndPoint;

CGPoint theStartPoint;

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 

{

UITouch *touch = [touches anyObject];

theEndPoint = [touch locationInView:self.view];

if((theEndPoint.x>Compass.frame.origin.x && theEndPoint.y>Compass.frame.origin.y) && (theEndPoint.x<Compass.frame.origin.x+Compass.frame.size.width && theEndPoint.y<Compass.frame.origin.y+Compass.frame.size.height))

{

float Centre_X = Compass.frame.origin.x + (Compass.frame.size.height/2);

float Centre_Y = Compass.frame.origin.y + (Compass.frame.size.width/2);

float dx=theEndPoint.x-Centre_X;

float dy=theEndPoint.y-Centre_Y;

double angle=atan2(dy,dx);

double br = RadiansTodegrees(angle);

CGAffineTransform rotate = CGAffineTransformMakeRotation(((br+90)/180)*3.14);

[arrow setTransform:rotate];

}

}