How to get mathemical PI constant in Swift

Question

I am trying to find a way to include the PI constant in my Swift code. I already found help in another answer, to import Darwin which I know gives me a

Answer 1

warning: 'M_PI' is deprecated: Please use 'Double.pi' or '.pi' to get the value of correct type and avoid casting.

surprisingly, .pi also works fine. M_PI is deprecated as of Swift 4.2.1, Xcode 10.1, which is the current version I am using. SO, Use .pi, or Double.pi