NOTICE: These packages probably don't work on ARM-based Macs or more recent versions of macOS. I don't know for sure because I don't use a Mac anymore. I'm leaving this repository up to avoid breaking people's builds, but I can't do much to help you with it. (You should consider migrating your software to a newer version of Qt.)
Please let me know at carter.sande@duodecima.technology if you are interested in maintaining this project.
This Homebrew tap allows you to install Qt4 (and various packages that depend on it) on macOS Sierra and newer. You can install it like this:
brew tap cartr/qt4
brew install qt@4
Feel free to submit an issue or pull request if you run into any problems or have any suggestions for improvements to the packages.
Please note: Qt4 is unsupported by its creators, so there are likely security/usability problems with it that will never be resolved. If you can, please consider migrating your projects to Qt5.
Install a separate brew with rosseta emulation:
https://stackoverflow.com/questions/64951024/how-can-i-run-two-isolated-installations-of-homebrew
Then install from the other brew (called brow in the answer)