Ios 以两个手指之间的点为中心缩放UIImageView

我使用CGAffineTransformScale实现了UIImageView的收缩缩放。 我会让缩放以两个手指之间的点为中心

我无法成功使用UIImageView的锚点来居中缩放

func handlePinchGesture(gesture: UIPinchGestureRecognizer) {

     if(gesture.state == .Began) {

        self.transitionView = UIImageView(image: self.imageView.image)

        if let view = transitionView {
             view.frame = CGRectMake(0, self.topImageViewConstraint.constant, self.imageView.frame.width, self.imageView.frame.height)
             self.view.addSubview(transitionView)
         }

         let locationInView:CGPoint = gesture.locationInView(self.transitionView)
         let locationInSuperview:CGPoint = gesture.locationInView(self.transitionView.superview)

         self.transitionView.layer.anchorPoint = CGPointMake(locationInView.x / self.transitionView.bounds.size.width, locationInView.y / self.transitionView.bounds.size.height)
         self.transitionView.center = locationInSuperview

    }

    if(gesture.state == .Began || gesture.state == .Changed) {

        self.transitionView.transform = CGAffineTransformScale(self.transitionView.transform, gesture.scale, gesture.scale)
        gesture.scale = 1

    }
}

编辑

第1步，夹点前的我的观点：

第2步，当在电子秤前调用挤压时

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只要我按下UIImageView（上面代码中的transitionView），图像就会移动。我不明白为什么会丢失帧位置。

我将滚动视图的偏移量添加到新的主播点。很好用

 let newAnchorPoint:CGPoint = CGPoint(x:locationInView.x , y: locationInView.y+self.scrollView.contentOffset.y)
 self.transitionView.layer.anchorPoint = CGPointMake(newAnchorPoint.x / self.transitionView.bounds.size.width, newAnchorPoint.y / self.transitionView.bounds.size.height)
 self.transitionView.center = CGPointMake(locationInSuperview.x , locationInSuperview.y)