Obj-C apps are not deprecated yet, so the approach in that GitHub repo must still work. That app is indeed written in C, but a big chunk is about building Obj-C classes and using other Obj-C objects - so it’s not quite C. You won't get much performance benefits or additional flexibility this way.
C is Turing-complete, so you can technically write anything in it. But on iOS, you'd need to build your own C library for application-level Apple SDKs, since Apple doesn't provide one. For simple apps (like small games or toy utils) - a minimal wrapper in Objective-C or Swift could be just a few hundred lines.
C is Turing-complete, so you can technically write anything in it. But on iOS, you'd need to build your own C library for application-level Apple SDKs, since Apple doesn't provide one. For simple apps (like small games or toy utils) - a minimal wrapper in Objective-C or Swift could be just a few hundred lines.