关于multi touches：多手势操作时anchorpoint的计算问题

ios代码中添加一个旋转的收拾识别UIRotationGestureRecognizer功能，在对应的target方法中如果加入一下代码：

if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
    UIView *piece = gestureRecognizer.view;
    CGPoint locationInView = [gestureRecognizer locationInView:piece];
    CGPoint locationInSuperview = [gestureRecognizer locationInView:piece.superview];

    piece.layer.anchorPoint = CGPointMake(locationInView.x / piece.bounds.size.width, locationInView.y / piece.bounds.size.height);
    piece.center = locationInSuperview;
}

请问这里的locationInView是指的哪个值，因为这里应该是有两个手指touch屏幕。