Download pre-built XCFrameworks from Release page.
iOS port of opencore-amr
Refer to README for opencore-amr info which is from original package.
Run build_ios.sh to build.
Then use opencore-amrnb.xcframework or opencore-amrwb.xcframework in output directory.
For AMR-WB encoding, refer to http://sourceforge.net/projects/opencore-amr/files/vo-amrwbenc/ or AMR Codecs as Shared Libraries http://www.penguin.cz/~utx/amr