Has anyone come across a Fortran 77 emulator or compiler for iOS devices?
Perhaps it's best done with a pre-compiler translating Fortran to C (and integrate that into Xcode as a separate build step). One such tool is e.g. http://www.greatmigrations.com/tools_gmFortran.aspx
Maybe one can also have a look at the gnu fortran compiler, as far as I remember it also started out as a precompiler translating Fortran to C. http://gcc.gnu.org/fortran/
It can be accomplished using the Dragonegg plugin for GCC (frontend), a generic LLVM installation (backend), and the Apple linker. I have been able to successfully build and run a 64-bit Fortran application on iOS 8.1 built on Mac OS X 10.10 using GCC 4.8 and LLVM 3.5. The process is not very straightforward and requires a number of hacks and some scripting, but the high-level steps are:
Now if you got this far, compile a Fortran source file into an iOS binary using:
Precompiled binaries for Dragonegg and libgfortran can be found here: http://download.zeroepoch.com/gfortran-ios/gfortran-ios.tar.bz2
UPDATE: The precompiled binaries archive now contains fat libraries (armv7s, arm64) and some bug fixes to the wrapper scripts.