Is there any library able to encode image data to ASTC texture on demand?
I am aware it is CPU intensive, but interested anyway.
https://github.com/ARM-software/astc-encoder is the reference compressor (created by ARM and AMD). It is probably not hard to get the source code working on an iOS device. It might be prohibitively slow, but it does offer various speed options so maybe one will strike the right balance between quality and speed for you.