It might make sense to differentiate between prototyping and implementation languages. As a design first company, they don't prototype in code, they use code t

It might make sense to differentiate between prototyping and implementation languages. As a design first company, they don't prototype in code, they use code to implement prototypes. With Swift they're just serving their own methodology. This also fits into their "we don't need to collect data" mindset, they seem to iterate on assumptions, not direct feedback from customers. They create many prototypes and then implement the most viable one, and and this point they know exactly what they need.