As Objective-C goes so does Apple. Even with Swift coming on board, Objective-C is still the foundation for all of Apple’s apps. Apple software development is dying by a thousand cuts.
C, C++ are big with IOT programmers due to the ability to cram more code onto tiny processors. Support is exceptional and the same can be said for Python - which is Python’s Ace up its sleeve. Measure support available for any programming language to determine it’s popularity and usage, IMO.