Adding to what the sibling comment from airspeedswift said, there is not ever a need to use dynamic dispatch in Swift outside of iOS apps. Idiomatic apps will h

Adding to what the sibling comment from airspeedswift said, there is not ever a need to use dynamic dispatch in Swift outside of iOS apps. Idiomatic apps will have many internal packages/targets that don't even import any Objective-C based libraries and can be compiled and run with just the swift toolchain. You can even inline all your frequent function calls. Idiomatic Swift also uses classes sparingly, and most are ideally declared final.