I'm the main maintainer of libsndfile.
libsndfile can be compiled and runs quite happily on Debian/Arm and also Android.
I would be surprised if no one has compiled it for iOS, but there are licensing issues. As you are no doubt aware, libsndfile is released under the LGPL which requires that one of the following conditions be met:
a) The library is used as a dynamically linked library (DLL on windows, shared object on Linux, dynlib on OSX etc).
b) All code that statically links to the LGPL library is released under a LGPL compatible license.
c) The library is used as a static library, but that all object files required to link the library against a new version be made available to all recipients of the application.
As I understand it, iOS does not support dynamically linked libraries (Android does) so option a) is out. That leaves you with options b) and c).
If you decide to go with option b) or c) then you still need to compile the library (and possibly it optional dependencies) for iOS and then link the library against your code.
]
