This primarily is advantageous for the big Objective-C applications which cannot be re-coded into Swift but would like to make a switch gradually. So, they both are compatible and can be used side by side, as of now at least. Or start using Objective-C routines in new Swift Projects. Slowly put in new Swift code into the existing Objective-C Project. That said, there are multiple approaches to how they can co-exist and how the developers can take advantage of this coexistence. They are not mutually exclusive but the intuitive design of Swift allows Objective-C to co-exist along with it.

The swift design allows it to be interoperable with Objective-C. But in the here and the now, the two must learn to coexist peacefully. Objective-C is showing its age and will, eventually, be much less prevalent. It’s no question - swift is the new toy and marked as the future. Swift on the other hand came into existence to replace an aging programming language with a modern technology platform. Objective-C was created and tuned for IOS development from birth.

Objective c to swift migration