This paper studies how developers use different programming languages in the iOS ecosystem by examining 161,883 releases of 25,231 third-party libraries spanning 11 years available through CocoaPods, a popular iOS dependency manager. Our empirical study shows that since its release, Swift has been widely adopted, but most libraries, even recent ones, still use Objective-C as their primary programming language. Looking at a small set of 38 open-source iOS apps, instead, we observe that apps are instead predominantly written in Swift by now. We also observe significant C usage across both libraries and apps. Our results suggest that analysis tools for iOS apps should not only support Swift, but also Objective-C and C code.