Alternatives to NSHost in iPhone app

Question

I'm currently using this code

    NSHost *host = [NSHost hostWithAddress:hostname];
if (host == nil) {
    host = [NSHost hostWithName:hostname];
    if (host == nil) {
        [self setMessage:@"Invalid IP address or hostname:"];
        return;
    }
}

to retrive my IP Address for a networking app I'm working on, however I'm aware that NSHost is a private API that will be rejected. Can anyone help me with working this code to produce the same results without using NSHost? I'm not really sure where to start.

EDIT:

Following suggestions that seem damn near perfect below I've added this code into my app in the place of the code above

    Boolean result;
CFHostRef hostRef;
CFArrayRef addresses;
NSString *hostname = @"www.apple.com";
hostRef = CFHostCreateWithName(kCFAllocatorDefault, (CFStringRef)hostname);
if (hostRef) {
    result = CFHostStartInfoResolution(hostRef, kCFHostAddresses, NULL); // pass an error instead of NULL here to find out why it failed
    if (result == TRUE) {
        addresses = CFHostGetAddressing(hostRef, &result);
    }
}
if (result == TRUE) {
    NSLog(@"Resolved");
} else {
    NSLog(@"Not resolved");
}

I've removed the 4th line (as I have this information from elsewhere already) but I get errors being based around CFHostRef being undeclared. How would I resolve that? It seems to be my only big hurdle, as other errors are only based upon the lack of being able to see hostRef after that. EDIT: Scratch that I also get kCFHostAddresses undeclared.

Answer 1

You can use CFHost to achieve the same. On the top of the CFHost Reference is a cookbook recipe for making the lookup.

The following code does very, very basic synchronous resolution (as yours above would with NSHost). Note that you don't want to do this since it can render your app unresponsive because it doesn't return until it's resolved or the timeout hits.

Use asynchronous lookup instead (CFHostSetClient and CFHostScheduleWithRunLoop as described in the CFHost documentation above). Also, depending on what you're planning to do, you may want to look into using the reachability APIs. Check out the WWDC sessions on networking available on the iPhone developer website.

Boolean result;
CFHostRef hostRef;
CFArrayRef addresses;
NSString *hostname = @"www.apple.com";
hostRef = CFHostCreateWithName(kCFAllocatorDefault, (CFStringRef)hostname);
if (hostRef) {
    result = CFHostStartInfoResolution(hostRef, kCFHostAddresses, NULL); // pass an error instead of NULL here to find out why it failed
    if (result == TRUE) {
        addresses = CFHostGetAddressing(hostRef, &result);
    }
}
if (result == TRUE) {
    NSLog(@"Resolved");
} else {
    NSLog(@"Not resolved");
}

// Don't forget to release hostRef when you're done with it

Answer 2

Look at this: http://blog.zachwaugh.com/post/309927273/programmatically-retrieving-ip-address-of-iphone

Answer 3

http://developer.apple.com/iphone/library/qa/qa2009/qa1652.html

Got a great little answer through the Developer Support system, this worked perfectly.