Egor Pugin announced on Firebird-Devel list :

With new CMake 3.2.1 it is possible to successfully build Firebird for

iOS platform using CMake.

Updated instructions for iOS build available at

https://bitbucket.org/egor_pugin/firebird_cmake/wiki/Home

The last issue you encounter during building is duplicate symbol error

from clang. It is related to class DatabaseDirectoryList in anonymous

namespace. This class exists in files: src/jrd/jrd.cpp and

src/common/db_alias.cpp.

For my tests I added last underscore symbol to one of those classes

and the build completes.