Zoom image while being pressed

imagePressed.swift

    func imagePressed(sender: ForceGestureRecognizer) {
        let point = sender.locationInView(self.view)
        let imageCoordPoint = CGPointMake(point.x - initialFrame.origin.x, point.y - initialFrame.origin.y)
        
        var xValue = max(0, imageCoordPoint.x / initialFrame.size.width)
        var yValue = max(0, imageCoordPoint.y / initialFrame.size.height)
        
        xValue = min(xValue, 1)
        yValue = min(yValue, 1)
        
        let anchor = CGPointMake(xValue, yValue)
        mainImageView.layer.anchorPoint = anchor
        let forceValue = max(1, sender.forceValue)
        mainImageView.layer.transform = CATransform3DMakeScale(forceValue, forceValue, 1)
        
        if sender.state == .Ended {
            mainImageView.layer.anchorPoint = CGPointMake(0.5, 0.5)
            mainImageView.layer.transform = CATransform3DIdentity
        }
    }