iOS support isn't working on 0.9.9

[henryiii]

Summary

I'm trying to use uv's iOS support directly in cibuildwheel, and I'm getting:

(AS)

Using CPython 3.13.9 interpreter at: /Library/Frameworks/Python.framework/Versions/3.13/bin/python3.13
Creating virtual environment at: /private/var/folders/6c/pzd640_546q6_yfn24r65c_40000gn/T/cibw-run-wu8a60og/cp313-ios_arm64_iphoneos/build/venv
Activate with: source /private/var/folders/6c/pzd640_546q6_yfn24r65c_40000gn/T/cibw-run-wu8a60og/cp313-ios_arm64_iphoneos/build/venv/bin/activate
error: Failed to inspect Python interpreter from active virtual environment at `/private/var/folders/6c/pzd640_546q6_yfn24r65c_40000gn/T/cibw-run-wu8a60og/cp313-ios_arm64_iphoneos/build/venv/bin/python3`
  Caused by: Querying Python at `/private/var/folders/6c/pzd640_546q6_yfn24r65c_40000gn/T/cibw-run-wu8a60og/cp313-ios_arm64_iphoneos/build/venv/bin/python3` returned an invalid response: unknown variant `iphoneos`, expected one of `aarch64`, `arm64`, `armv5tel`, `armv6l`, `armv7l`, `armv8l`, `powerpc64le`, `ppc64le`, `powerpc64`, `ppc64`, `powerpc`, `ppc`, `i386`, `i686`, `x86`, `amd64`, `x86_64`, `s390x`, `loongarch64`, `riscv64`, `wasm32`

(Intel)

Using CPython 3.13.9 interpreter at: /Library/Frameworks/Python.framework/Versions/3.13/bin/python3.13
Creating virtual environment at: /private/var/folders/vx/zmvzwd094y53mqcpn3jbm7580000gn/T/cibw-run-bcaei7sg/cp313-ios_x86_64_iphonesimulator/build/venv
Activate with: source /private/var/folders/vx/zmvzwd094y53mqcpn3jbm7580000gn/T/cibw-run-bcaei7sg/cp313-ios_x86_64_iphonesimulator/build/venv/bin/activate
error: Failed to inspect Python interpreter from active virtual environment at `/private/var/folders/vx/zmvzwd094y53mqcpn3jbm7580000gn/T/cibw-run-bcaei7sg/cp313-ios_x86_64_iphonesimulator/build/venv/bin/python3`
  Caused by: Querying Python at `/private/var/folders/vx/zmvzwd094y53mqcpn3jbm7580000gn/T/cibw-run-bcaei7sg/cp313-ios_x86_64_iphonesimulator/build/venv/bin/python3` returned an invalid response: unknown variant `iphonesimulator`, expected one of `aarch64`, `arm64`, `armv5tel`, `armv6l`, `armv7l`, `armv8l`, `powerpc64le`, `ppc64le`, `powerpc64`, `ppc64`, `powerpc`, `ppc`, `i386`, `i686`, `x86`, `amd64`, `x86_64`, `s390x`, `loongarch64`, `riscv64`, `wasm32`

iphoneos and iphonesimulator seem to be confusing it. From Discord. CC @freakboy3742. pypa/cibuildwheel#2586

Platform

macOS

Version

0.9.9

Python version

3.13

[konstin]

The PEP talks about the (private?) sys.implementation._multiarch and platform.ios_ver(), @freakboy3742 do you know how those relate to sysconfig.get_platform(), the main value that uv currently reads?

[freakboy3742]

@konstin I have no knowledge at all about how uv is handling this.

From the Python side, sysconfig.get_platform() is internally constructed as {sys.platform}-{min_ios_version}-{sys._implementation.multiarch}.

In practice, this means:

ARM64 device:

• sys._implementation.multiarch returns arm64-iphoneos
• platform.ios_ver() returns a namedtuple (system="iOS", release="18.6", model="iPhone16,4", is_simulator=False). The release and model is the actual iOS version and internal device name of the running device. System will return iPad on an iPad.
• sysconfig.get_platform() returns ios-13.0-arm64-iphoneos

ARM64 simulator:

• sys._implementation.multiarch returns arm64-iphonesimulator
• platform.ios_ver() returns a namedtuple (system="iOS", release="13.0", model="iphoneos", is_simulator=True)
• sysconfig.get_platform() returns ios-13.0-arm64-iphonesimulator

x86-64 simulator:

• sys._implementation.multiarch returns x86_64-iphonesimulator
• platform.ios_ver() returns a namedtuple (system="iOS", release="13.0", model="iphoneos", is_simulator=True)
• sysconfig.get_platform() returns ios-13.0-x86_64-iphonesimulator .

The references to 13.0 describe the minimum supported iOS version, which is a function

If the interpreter is being started in cibuildwheel, then it's running on macOS; depending on exactly how the interpreter was started, it may be in a "fake" virtual environment - a venv that has a .pth file that monkey patches key values in sys, platform, sysconfig and os to return iOS-like values.

You can get an isolated version of that environment handling in xbuild. xbuild contains xvenv, which converts a "real" macOS venv in to a "fake" iOS, Android or Emscripten venv; xbuild is an extension of build that creates cross-platform environments and starts a cross-platform build. It's enough of a fake to convince pip to install iOS/Android wheels; and provided the rest of the environment variables are set up appropriately, to manage compiling binary wheels.

Happy to provide any additional details that might be helpful.

[samypr100]

Interesting that Android is working in cibuildwheel but not iOS.

[henryiii]

Android doesn't have "simulator" vs "device" separate binaries, iOS does. I think that's why it's more complicated.