Opinionation Incoming! Objective-C is completely irrelevant outside of Apple because Interface Builder was the killer app for Objective-C and there was never a version that worked well with anything except AppKit -- even UIKit has always been painful to use with it. iOS developers had to tolerate Objective-C, but no one else bothered.

It's a shame, because Foundation.framework circa 1994 was a better standard library than any other language had at the time. Many have caught up since!

Swift has many virtues outside of SwiftUI -- real static typing, functional, sophisticated generics without all the gotchas of C++ templates, complete ABI, efficient exceptions, the syntax isn't so foreign to people used to C++/Java/Rust/Ruby/Python; I could go on and on.

I've written Objective-C code for 23ish years, and I like it a lot, but no one entering the workforce cares about its remaining virtues and the language has been mostly unchanged for almost two decades.