Simple Obj-C function to calculate centroid of points

CentroidCalculator.m

CGPoint centroidOfPoints(const CGPoint* points, int pointCount) {
    CGPoint centroid = CGPointMake(0, 0);
    double x0, y0, x1, y1, partialArea;
    double signedArea = 0.0;
    
    for (int index = 0; index < pointCount; index++) {
        int nextIndex = (index == pointCount-1) ? 0 : index+1;
        
        x0 = points[index].x;
        y0 = points[index].y;
        x1 = points[nextIndex].x;
        y1 = points[nextIndex].y;
        partialArea = (x0 * y1) - (x1 * y0);
        
        signedArea += partialArea;
        centroid.x += (x0 + x1) * partialArea;
        centroid.y += (y0 + y1) * partialArea;
    }
    
    signedArea /= 2;
    centroid.x /= (6.0 * signedArea);
    centroid.y /= (6.0 * signedArea);
    
	NSLog(@"Signed Area: %E", signedArea);
    
    return centroid;
};