I don't have any experience with Swift, but how to you approach unit testing with everything `final`? Being able to inject mock subclasses is a staple of OO testing.
I don't know Swift, but I know I testing... your constructors should be accepting interfaces (for things that are complex enough that you'd want to mock them), not concrete types. In Swift I gather you'd use protocols.
Shrug... at least in the Java world, modern mocking frameworks render obsolete the J2EE-era "interfaces for the sake of interfaces" boilerplate. On the other hand, none of them work if the class you're mocking is `final`.
Protocols and generics cover everything you need to do that. Idiomatic Swift makes little use of classes to begin with, it's mostly structs, enums, and protocols, none of which allow inheritance.
