Comment on How can I resolve the xcode12.4 build error: Use of undeclared identifier '_CTYPE_A'? For anyone else having this issue, see the solution posted here. Turned out to be a conflict involving openSSL - https://stackoverflow.com/questions/79034494/xcode-16-error-use-of-undeclared-identifier-ctype-a/79077043#79077043 Developer Tools & Services Xcode Oct ’24