func withVaList<R>(_: [CVarArg], _: (CVaListPointer) -> R) Invokes the given closure with a C va_list argument derived from the given array of arguments. The pointer passed as an argument to body is valid only for the lifetime of the closure. Do not escape it from the closure for later use. Parameters: args: An array of arguments to convert to a C va_list pointer. body: A closure with a CVaListPointer parameter that references the arguments passed as args. If body has a return value, it is used as the return value for the withVaList(_:) function. The pointer argument is valid only for the duration of the closure's execution. Returns: The return value of the body closure parameter, if any. See Also: getVaList(_:) Declaration func withVaList<R>(_ args: [CVarArg], _ body: (CVaListPointer) -> R) -> R