The app is monetized by limiting the number of “runs” you can do per month. Based on iOS limitations I think we can assume this means the compilation is done on a remote server.
EDIT: nevermind! I tried running a program with airplane mode on and it still worked. Now I’m really interested to hear how this was accomplished.
EDIT: nevermind! I tried running a program with airplane mode on and it still worked. Now I’m really interested to hear how this was accomplished.