Has somebody succeed to build it for iOS?
I am not aware of any project that used OpenFHE in iOS.
But in principle, OpenFHE is a C++ library and iOS does support C++ development. You only need to write a wrapper in Objective-C++ and link it to the OpenFHE library.
I want to also add that Apple clang is supported by OpenFHE (it is used when building in macOS or iOS).