Damien Romito Damien Romito - 1 year ago 310
iOS Question

Objective C - How to get the public IP address of the device

I found this sample code to get all local IP addresses, but I don't find an easy solution to get the public IP.

A legacy class from Apple allowed to do that
... but it's legacy ...

Answer Source

I have used ALSystemUtilities in the past. You basically have to make a call externally to find this out.

+ (NSString *)externalIPAddress {
    // Check if we have an internet connection then try to get the External IP Address
    if (![self connectedViaWiFi] && ![self connectedVia3G]) {
        // Not connected to anything, return nil
        return nil;

    // Get the external IP Address based on dynsns.org
    NSError *error = nil;
    NSString *theIpHtml = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://www.dyndns.org/cgi-bin/check_ip.cgi"]
    if (!error) {
        NSUInteger  an_Integer;
        NSArray *ipItemsArray;
        NSString *externalIP;
        NSScanner *theScanner;
        NSString *text = nil;

        theScanner = [NSScanner scannerWithString:theIpHtml];

        while ([theScanner isAtEnd] == NO) {

            // find start of tag
            [theScanner scanUpToString:@"<" intoString:NULL] ;

            // find end of tag
            [theScanner scanUpToString:@">" intoString:&text] ;

            // replace the found tag with a space
            //(you can filter multi-spaces out later if you wish)
            theIpHtml = [theIpHtml stringByReplacingOccurrencesOfString:
                         [ NSString stringWithFormat:@"%@>", text]
                                                             withString:@" "] ;
            ipItemsArray = [theIpHtml  componentsSeparatedByString:@" "];
            an_Integer = [ipItemsArray indexOfObject:@"Address:"];
            externalIP =[ipItemsArray objectAtIndex:++an_Integer];
        // Check that you get something back
        if (externalIP == nil || externalIP.length <= 0) {
            // Error, no address found
            return nil;
        // Return External IP
        return externalIP;
    } else {
        // Error, no address found
        return nil;

Source from ALSystemUtilities

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