How to get Ip address in swift

Question

How do i get my local IpAddress?

I tried to use this Obj C example: how to get ip address of iphone programmatically

When i get to the function getifaddrs() i can't get any further. i can't use the function.

Is there an alternative way to do this, or am I approaching this the wrong way?

Answer 1

As it turned out in the discussion, OP needs the interface address on a Mac and not on an iOS device as I thought initially. The code referenced in the question checks for the interface name "en0", which is the WiFi interface on the iPhone. On a Mac it makes more sense to check for any "up-and-running" interface instead. Therefore I have rewritten the answer. It is now a Swift translation of the code in Detect any connected network.

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getifaddrs() is defined in <ifaddrs.h>, which is not included by default. Therefore you have to create a bridging header and add

#include <ifaddrs.h> 

The following function returns an array with the names of all local "up-and-running" network interfaces.

func getIFAddresses() -> [String] {     var addresses = [String]()      // Get list of all interfaces on the local machine:     var ifaddr : UnsafeMutablePointer<ifaddrs> = nil     if getifaddrs(&ifaddr) == 0 {          // For each interface ...         var ptr = ifaddr         while ptr != nil {             defer { ptr = ptr.memory.ifa_next }               let flags = Int32(ptr.memory.ifa_flags)             let addr = ptr.memory.ifa_addr.memory              // Check for running IPv4, IPv6 interfaces. Skip the loopback interface.             if (flags & (IFF_UP|IFF_RUNNING|IFF_LOOPBACK)) == (IFF_UP|IFF_RUNNING) {                 if addr.sa_family == UInt8(AF_INET) || addr.sa_family == UInt8(AF_INET6) {                      // Convert interface address to a human readable string:                     var hostname = [CChar](count: Int(NI_MAXHOST), repeatedValue: 0)                     if (getnameinfo(ptr.memory.ifa_addr, socklen_t(addr.sa_len), &hostname, socklen_t(hostname.count),                         nil, socklen_t(0), NI_NUMERICHOST) == 0) {                         if let address = String.fromCString(hostname) {                             addresses.append(address)                         }                     }                 }             }         }         freeifaddrs(ifaddr)     }      return addresses } 

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Update for Swift 3: In addition to adopting the code to the many changes in Swift 3, iterating over all interfaces can now use the new generalized sequence() function:

func getIFAddresses() -> [String] {     var addresses = [String]()      // Get list of all interfaces on the local machine:     var ifaddr : UnsafeMutablePointer<ifaddrs>?     guard getifaddrs(&ifaddr) == 0 else { return [] }     guard let firstAddr = ifaddr else { return [] }      // For each interface ...     for ptr in sequence(first: firstAddr, next: { $0.pointee.ifa_next }) {         let flags = Int32(ptr.pointee.ifa_flags)         let addr = ptr.pointee.ifa_addr.pointee          // Check for running IPv4, IPv6 interfaces. Skip the loopback interface.         if (flags & (IFF_UP|IFF_RUNNING|IFF_LOOPBACK)) == (IFF_UP|IFF_RUNNING) {             if addr.sa_family == UInt8(AF_INET) || addr.sa_family == UInt8(AF_INET6) {                  // Convert interface address to a human readable string:                 var hostname = [CChar](repeating: 0, count: Int(NI_MAXHOST))                 if (getnameinfo(ptr.pointee.ifa_addr, socklen_t(addr.sa_len), &hostname, socklen_t(hostname.count),                                 nil, socklen_t(0), NI_NUMERICHOST) == 0) {                     let address = String(cString: hostname)                     addresses.append(address)                 }             }         }     }      freeifaddrs(ifaddr)     return addresses } 

Answer 2

Answering to Is there an alternative way to getifaddrs() for getting the ip-address?

Yes, there is an alternative way. You can also get the ip address by utilizing ioctl(). The cleanest way would be doing it in C and then wrapping it up in Swift. So consider this:

Create a C Source File (Xcode should create it together with a .h) and remember adding the header into your project's bridging header, or into umbrella-header if you have a cocoa touch framework.

Add the following into your .c source and method's declaration into .h:

#include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <netinet/in.h> #include <net/if.h>  int _interfaceAddressForName(char* interfaceName, struct sockaddr* interfaceAddress) {      struct ifreq ifr;     int fd = socket(AF_INET, SOCK_DGRAM, 0);     ifr.ifr_addr.sa_family = AF_INET;      strncpy(ifr.ifr_name, interfaceName, IFNAMSIZ-1);      int ioctl_res;     if ( (ioctl_res = ioctl(fd, SIOCGIFADDR, &ifr)) < 0){         return ioctl_res;     }      close(fd);     memcpy(interfaceAddress, &ifr.ifr_addr, sizeof(struct sockaddr));     return 0; } 

Your Swift wrapper might look something like:

public enum Error:ErrorType {     case IOCTLFailed(Int32)     case StringIsNotAnASCIIString }  public func interfaceAddress(forInterfaceWithName interfaceName: String) throws -> sockaddr_in {      guard let cString = interfaceName.cStringUsingEncoding(NSASCIIStringEncoding) else {         throw Error.StringIsNotAnASCIIString     }      let addressPtr = UnsafeMutablePointer<sockaddr>.alloc(1)     let ioctl_res = _interfaceAddressForName(strdup(cString), addressPtr)     let address = addressPtr.move()     addressPtr.dealloc(1)      if ioctl_res < 0 {         throw Error.IOCTLFailed(errno)     } else {         return unsafeBitCast(address, sockaddr_in.self)     } } 

Then you can use it in your code like:

let interfaceName = "en0" do {     let wlanInterfaceAddress = try interfaceAddress(forInterfaceWithName: interfaceName)     print(String.fromCString(inet_ntoa(wlanInterfaceAddress.sin_addr))!) } catch {     if case Error.IOCTLFailed(let errno) = error where errno == ENXIO {         print("interface(\(interfaceName)) is not available")     } else {         print(error)     } } 

en0 typically is the interface you need, which stands for WLAN

If you also need to know available interface names you can utilize if_indextoname():

public func interfaceNames() -> [String] {      let MAX_INTERFACES = 128;      var interfaceNames = [String]()     let interfaceNamePtr = UnsafeMutablePointer<Int8>.alloc(Int(IF_NAMESIZE))     for interfaceIndex in 1...MAX_INTERFACES {         if (if_indextoname(UInt32(interfaceIndex), interfaceNamePtr) != nil){             if let interfaceName = String.fromCString(interfaceNamePtr) {                 interfaceNames.append(interfaceName)             }         } else {             break         }     }      interfaceNamePtr.dealloc(Int(IF_NAMESIZE))     return interfaceNames }