objective-c - Zooming UIView inside a ScrollView via Pinch gesture on a Point

Question

Due to some requirements I'm zomming subview of UIScrollView with UIPinchGestureRecognizer and not using UIScrollView's default zooming. In selector of gesture I resize my subview with a factor and reset contentSize of UIScrollView. It's working perfectly. The problem is that when I resize the frame of subview then it's increased or decreased in one direction. I want it to zoomin/zoomout on touched point like in a UIScrollView or in Gallery of iOS. How can I achieve this?