How to scale NSView from center with Facebook Pop animation?

Please note that this is a Mac OS X ( NSView

) related question.

I'm trying to use Facebook POP animation to scale an NSView from center (to 75% of its size) and then back to 100%, however I can't seem to get it to work. Considering what kPOPLayerScaleXY

doesn't seem to work, I did the following, but it gives me the wrong results (since it seems to scale down from the top left, and when zoomIn

false, it gets too large:

  CGRect baseRect = CGRectMake(0, 0, 30, 24);
  CGFloat scale = (zoomIn) ? 0.75 : 1.0;

  CGFloat x = baseRect.origin.x;
  CGFloat y = baseRect.origin.y;
  CGFloat width = baseRect.size.width;
  CGFloat height = baseRect.size.height;

  if (zoomIn) {
    width -= floorf((1.0 - scale) * width);
    height -= floorf((1.0 - scale) * height);

    x += floorf((width * (1.0f - scale)) / 2);
    y += floorf((height * (1.0f - scale)) / 2);
  }

  CGRect scaleRect = CGRectMake(x, y, width, height);

  [myView.layer pop_removeAllAnimations];

  POPSpringAnimation *animation = [POPSpringAnimation animationWithPropertyNamed:kPOPLayerBounds];
  animation.springBounciness = 8;
  animation.toValue = [NSValue valueWithCGRect: scaleRect];
  [myView.layer pop_addAnimation:animation forKey:@"zoom"];