So Objective-C is kinda old school, but it certainly influenced the development and design of Swift, so its legacy certainly lives on. And not all new apps or applications are developed in Swift today either. There’s strong reasons to keep using Objective-C, including ease of access to low-level data structures, simplicity, and control.
Objective-C is an object-oriented flavor of C, with some slightly different constructs than what we’re used to (I’m looking at you Protocols). Let’s take a look at how Objective-C implements Classes, one of the primary design elements of any object-oriented language.