Yes, it's still technically possible to write an iOS app in plain C in 2025 — but with caveats. You’ll need to wrap your C code in a minimal Objective-C or Swift layer to satisfy UIKit/AppKit requirements and Xcode’s project structure. Apple’s SDKs are built around Obj-C/Swift, so things like UI, lifecycle, and event handling need some glue code. The CBasediOSApp repo you linked is still a good starting point, but expect to adapt it for modern toolchains and signing requirements. Realistically, you'd write most logic in C (e.g. a game engine, parser, or core library) and interface with minimal Obj-C or Swift for the UI. Anyone trying it in 2025 will likely be doing it for fun, education, or embedded-style constraints — not App Store production unless there’s a really good reason.