Percentage for two CGRect comparaison

How can i get percentage for comparaison for two rects?

Examples:

if r1(0, 0, 150, 150) r2(0, 0, 150, 150) so receive 100%.

if r1(0, 0, 150, 150) r2(75, 0, 150, 150) so receive 50%.

I need some function that receive two rectangles and return percentage how much there are similar.. I need the percentage of the overlapping area of the two rectangles

Thanks for your help :-)

Try This;

var r1:CGRect = CGRect(x: 0, y: 0, width: 150, height: 150);
var r2:CGRect = CGRect(x: 75, y: 0, width: 150, height: 150);
//--
var per = rectIntersectionInPerc(r1, r2: r2);
NSLog("per : \(per)) %");

-

//Width and Height of both rects may be different
func rectIntersectionInPerc(r1:CGRect, r2:CGRect) -> CGFloat {
    if (r1.intersects(r2)) {

       //let interRect:CGRect = r1.rectByIntersecting(r2); //OLD
       let interRect:CGRect = r1.intersection(r2);

       return ((interRect.width * interRect.height) / (((r1.width * r1.height) + (r2.width * r2.height))/2.0) * 100.0)
    }
    return 0;
}