Easy way to convert coordinate systems between three views?

Question

It's quiet complicated. I have four UIViews.

viewA acts as root container. viewB and viewC are childs of viewA. So viewA contains viewB and viewC.

viewD is a child of viewB.

I try to "draw" it for you:

viewA OWNS ((viewB OWNS viewD) && viewC)

I rotate the layer's transform.rotation.z of viewB. So viewB is rotated a little bit. ViewD is also rotated a little bit relative to viewB.

Also, I rotate viewC the same way with an other value. So both viewB and viewC are rotated differently relative to viewA. viewD is rotated a little bit relative to viewB.

I need to convert all these coordinate systems in such a way, that the rotation of viewC can be specified relative to viewD. Or in other words: In such a way, that when the transform.rotation.z of viewC is the same as from viewD, both views appear to be rotated the same way (visually on screen).

A few weeks ago I was reading in some paper that UIKit provides support for converting coordinate systems. Any idea if they're suitable to fix this problem?

Answer 1

It sounds like you want viewD's transform to be independent of viewB? If so, make viewD a subview of viewA (if it's a later sibling than viewB, it will appear on top of it).