It shows how to handle 3GP(AMR-NB) audio file format in iOS.
Just locate 3GP file into the application documents dir.
It uses "Opencore-amr"("Opencore-amr-iOS") codec library.
For convenience, it is included in the repository.
This example has no license because it is just sample code.
But "Opencore-amr" & "AMR" & "3GP" have an own license and patent.
Please check out above when you use for commercial purpose.