I currently have the need to execute prolog code in an application I am making. I am aware that Apple probably never would allow something like this in the App Store, but that i
Half a year later, I would just like to provide some insight on this. I ended up writing a server with an interface to prolog in Java, accepting prolog calls through TCP. It works almost exactly like the live prolog interpreter SWI-prolog (among others) provides, and mostly works quite well. However, it is far from an optimal solution, as you can't call functions from inside prolog. You lose the possibility of having two-way communication.
If I were to start all over again, I would certainly have tried harder to compile one of the pure C implementations for iOS. I gave it a quick go, but my lack of experience stopped me from even removing all of the errors I got. Judging by the fact that you cannot have prolog running as a background process on a unmodified version of iOS as well, some major rewriting would have to be done. Because of this, one might just have to write a new implementation (perhaps inspired by some of the more lightweight ones out there) from scratch to get the perfect solution.