swiftdoc.org | Auto-generated documentation for Swift | Generator Utils library

You cannot call a C function taking a variable argument list from Swift. You'll need a variant taking a va_list parameter (similar to printf and vprintf):

You can use numericCast() to convert between different integer types. As the documentation states:

Typically used to do conversion to any contextually-deduced integer type.

In your case:

Type names starting with an underscore should always treated as internal. In Swift 3.1, it is marked as internal in the source code and therefore not publicly visible.

Using _ArrayProtocol was a workaround in earlier Swift versions where you could not define an Array extension with a "same type" requirement. This is now possible as of Swift 3.1, as described in the Xcode 8.3 release notes:

Constrained extensions allow same-type constraints between generic parameters and concrete types. (SR-1009)

Using the internal protocol is therefore not necessary anymore, and you can simply define