I actually think we're at the point where it's an irresponsible business decision to build an iOS app in Swift over Javascript in most cases. React Native can target both iOS + Android with a much better development workflow than Swift can offer.

Why on earth would you want to use Swift when it's harder and more time consuming to implement, takes longer to learn, has worse library support, is harder to hire for, and only targets one platform? Apple really dropped the ball with Swift.

I suppose that "performance mandates it" is a valid reason for wanting to use Swift. But I think for 95% of apps Swift is the wrong technology choice.