Why carotene is not enabled for iOS

In CMakeLists.txt:
OCV_OPTION(WITH_CAROTENE “Use NVidia carotene acceleration library for ARM platform” ON

VISIBLE_IF (ARM OR AARCH64) AND NOT IOS)

I want to accelerate OpenCV using carotene on iOS devices. But it seems carotene doesn’t support iOS? Why?
For accelerating OpenCV on iOS devices, what’s the best choice? Halide?
Thanks