In double-checking, posts like the following make me think that Xcode 9.4 is the last version which supports compiling for i386: https://developer.apple.com/forums/thread/108704 This would make your 32 bit setup require macOS 10.14 + Xcode 9.4.

To clarify, I added Alex in CC. Alex: What is your current build setup (OS and Xcode version) for building fat libs with 32 bit Intel (i386) for distribution?

On Jun 8, 2022, at 8:04 PM, Dan Wilcox <danomatika@gmail.com> wrote:

As to which versions of macOS (that's the official name for some years now) to build on, I believe you can still build the i386 arch with Xcode on macOS 10.15, so judging from the following it may be Xcode 11 or 12: https://xcodereleases.com. I think Alex Porres is using this set up, so maybe he can chime in with his combo of OS and Xcode. The irony is that you can't run the 32 bit arch on 10.15, but at least you can build for it. Xcode on macOS 11 (version after 10.15) only allows for building x64_64 and arm64.

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Dan Wilcox
@danomatika
danomatika.com
robotcowboy.com