When Apple first introduced Swift at WWDC 2014, my first thought was how much work it would be for developers to rewrite their apps in Swift, which are currently written in Objective-C. I also wondered why a developer would rewrite their apps in Swift. A lot of these applications are pretty complex and would take a pretty large effort to rewrite them. Somewhere in the Swift presentation, Apple spoke about mix and match, which allows Swift and Objective-C to interact within the same project. Mix and match sure sounded like an ideal solution because developers could rewrite sections of their code in Swift as they needed to do updates instead of having to rewrite their whole application. My big question was how well mix and match would actually work, and I was very surprised, not only did it work well, but it was also easy to implement.

In this chapter, we will cover the following topics: