Resize UIImage/UIImageView without keeping aspect ratio

Question

I have a UIImageView that I've added a PinchGestureRecognizer to. Currently, the image is resized nicely when pinching, but I want to be able to resize the image without maintaining the aspect ratio. So if the user pinches horizontally, the image view's width would enlarge; if they pinch vertically, the height would enlarge and so forth.

Can anyone give me a hint on how I could do that please?

Answer 1

Write a custom gesture recognizer that requires two fingers to be on screen.
Once both fingers are on screen store their offset to the imageView's border in some UIEdgeInsets.

In touchesMoved, check if both fingers are onscreen: if so, calculate the new frame by applying the edgeInsets in the current touch position.

Header: click
Implementation: click

Works well and feels more natural than other implementations I've seen.

Answer 2

You would need to do the touch handling yourself as UIPinchGestureRecognizer only supports one scale which has no concept of being pinched horizontally or vertically.

You could create your own subclass of UIGestureRecognizer (see here for docs ) which looked at the horizontal and vertical separation of the touch points to determine 2 different scales. It should be fairly straightforward to create I would have thought. Just look at the initial touch points and then when they move, calculate the difference in the current separation of the touches to the initial separation of the touches, in both the vertical and horizontal directions.