How to include in Swift language

Question

I have an Objective-C class which have

#include <arpa/inet.h>

But how to include this in Swift language?

Answer 1

You can't include a C header directly in a Swift source code file. Instead include the C header in an Objective C header file, and add a bridging header that includes all the needed Objective C headers to the Xcode project.

Answer 2

Some of the functions defined in <arpa/inet.h> are available if you import Foundation or Darwin.

However, understanding how to use them will take some work. You should create a playground or use the command-line REPL to experiment. Example:

$ xcrun swift
"crashlog" and "save_crashlog" command installed, use the "--help" option for detailed help
"malloc_info", "ptr_refs", "cstr_refs", and "objc_refs" commands have been installed, use the "--help" options on these commands for detailed help.
Welcome to Swift!  Type :help for assistance.
  1> import Foundation
  2> inet_addr("10.0.1.1")
$R6: in_addr_t = {
  value = 16842762
}
  3> var a = in_addr(s_addr: 16842762)
a: in_addr = {
  s_addr = {
    value = 16842762
  }
}
  4> inet_netof(a)
$R7: in_addr_t = {
  value = 10
}
  5> 

You will probably find that the functions that deal with C strings (like inet_ntoa) are just too difficult to work with. It would probably be easier for you to just write a wrapper class in Objective-C that provides a class method for each <arpa/inet.h> function you are interested in. The class methods can translate between raw C strings and NSStrings. Then you can call on the class methods of this Objective-C wrapper from your Swift code.