While Swift is the hot new language right now in the Apple development community, there is no immediate sign that Objective-C is getting replaced fully. All of Apple's APIs are still written in Objective-C and it would be a lot of work for Apple to rewrite them, if they even wanted to. Apple definitely designed Swift to be able to live alongside Objective-C, so for now we have to assume that Objective-C is here to stay. This makes understanding and being able to interact with Objective-C very valuable, even as a Swift developer.
In this chapter, we have gotten an overview of the most pertinent Objective-C features and syntax from the point of view of a primarily Swift developer. We have learned how Swift is basically a part of a long line of evolving languages. It was heavily influenced by Apple's desire to make it backwards compatible with Objective-C and Objective-C was actually an evolution of C which was an evolution of Assembly and so on. Objective-C is still a powerful language with the ability to express many of the same concepts as Swift. Objective-C has similar concepts of constants and variables with more of a stress on variables. It also has the same basic containers but control flow is slightly different in the two languages. Swift has more powerful switches and ranges, but the underlying concepts are still very much the same. Functions are almost identical between the two languages but the type system in Objective-C is somewhat more limited because it can only express classes unlike Swift which has a powerful concept of classes, structures, and enumerations. Structures and enumerations still exist in Objective-C, but they really come directly from C and can do a lot less. Finally, we saw that organizing Objective-C in a project is very much the same and calling Objective-C code from Swift is actually quite straightforward.
There is some debate in the Apple developer community about how relevant Objective-C will be moving forward. There are people that have jumped into Swift development full time and there are others that are waiting for Swift to mature even more before they commit energy to truly learning it. However, there is little debate over the fact that Objective-C knowledge is still going to be relevant for a while, most notably because of the vast resources that exist and the fact that all existing Apple APIs are written in Objective-C. We will put those APIs to use in our next chapter: Chapter 11, A Whole New World – Developing an App, when we will finally dive into some real app development.