CODEWITHSUNDEEP
iphoneobjective-ccocoacocoa-touchnetwork-programming
Richard Stelling
Richard Stelling

Reputation: 25665

How to write a simple Ping method in Cocoa/Objective-C

I need to write a simple ping method in Cocoa/Objective-C. It also needs to work on the iPhone.

I found an example that uses icmp, will this work on the iPhone?

I'm leaning towards a solution using NSNetServices, is this a good idea?

The method only needs to ping a few times and return the average and -1 if the host is down or unreachable.

Upvotes: 22

Views: 39526

Answers (7)

Gene Myers
Gene Myers

Reputation: 1290

NOTE- I would recommend Chris' solution below which actually answers the question asked, directly. This post from 12 years ago was in response to the original authors upvoted answer, to which I had a better solution. As the author upvoted the answer above that used Reachability, I assumed that he was in fact more interested in reachability than actually in sending a ping, hence my answer. Please consider this before downvoting this answer.

StreamSCNetworkCheckReachabilityByName is deprecated and NOT available for the iPhone. Note: SystemConfiguration.framework is required

bool success = false;
const char *host_name = [@"stackoverflow.com" 
                         cStringUsingEncoding:NSASCIIStringEncoding];

SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL,
                                                                        host_name);
SCNetworkReachabilityFlags flags;
success = SCNetworkReachabilityGetFlags(reachability, &flags);

//prevents memory leak per Carlos Guzman's comment
CFRelease(reachability);

bool isAvailable = success && (flags & kSCNetworkFlagsReachable) && 
                             !(flags & kSCNetworkFlagsConnectionRequired);
if (isAvailable) {
    NSLog(@"Host is reachable: %d", flags);
}else{
    NSLog(@"Host is unreachable");
}

Upvotes: 37

Chris
Chris

Reputation: 40661

I had this same problem, and ended up writing a simple wrapper around SimplePing to achieve this, wrote a blog about it and there's some code on github, hopefully will help someone here:

http://splinter.com.au/how-to-ping-a-server-in-objective-c-iphone

Upvotes: 32

Monobono
Monobono

Reputation: 780

Pinging on the iPhone works a bit different than on other platforms, due to the fact that you don't have root access. See this sample code from Apple.

Upvotes: 5

Zhami
Zhami

Reputation: 19153

You are not missing anything -- "Reachability" doesn't actually test that the target domain is in fact reachable, it only assesses if there is a pathway out of the machine by which the target domain is potentially reachable. So long as you have some outbound connection (e.g., an active wirless or wired connection), and a routing configuration that leads to the target, then the site is "reachable" as far as SCNetworkReachability is concerned.

Upvotes: 13

Chris Bennet
Chris Bennet

Reputation: 617

The answer Gene Myers posted works using "SCNetworkReachabilityCreateWithName" for me - but only in the simulator. On my device (iPod w/OS 2.2.1) it always returns "Host is reachable" even for nonsense addresses like "zzz".

Am I misunderstanding something? Thanks.

Here's my code just in case:

From How to write a simple Ping method in Cocoa/Objective-C

    - (IBAction) TestReachability:(id)sender
{
    bool success = false;
    const char *host_name = [ipAddressText.textcStringUsingEncoding:NSASCIIStringEncoding];
    NSString *imageConnectionSuccess = @"Connected.png";
    NSString *imageConnectionFailed = @"NotConnected.png";

    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL,
                                                                                host_name);
    SCNetworkReachabilityFlags flags;
    success = SCNetworkReachabilityGetFlags(reachability, &flags);
    bool isAvailable = success && (flags & kSCNetworkFlagsReachable) && 
        !(flags & kSCNetworkFlagsConnectionRequired);
    if (isAvailable)
    {
        NSLog([NSString stringWithFormat: @"'%s' is reachable, flags: %x", host_name, flags]);
        [imageView setImage: [UIImage imageNamed:imageConnectionSuccess]]; 
    }
    else
    {
        NSLog([NSString stringWithFormat: @"'%s' is not reachable", host_name]);
        [imageView setImage: [UIImage imageNamed:imageConnectionFailed]]; 
    }
}

Upvotes: 0

Jark
Jark

Reputation: 1

Please take note that there is an difference between the simulator and the actual iPhone. The simulator is not a true simulator like the one supplied by Android, it uses Mac OSX classes for most of the functions.

This is particularly hell if there is a difference between the Mac OSX and iPhonew(for example the keychain).

Upvotes: -1

Stream
Stream

Reputation: 9493

The code below seems to be working synchronously:

const char *hostName = [@"stackoverflow.com"
                        cStringUsingEncoding:NSASCIIStringEncoding];
SCNetworkConnectionFlags flags = 0;
if (SCNetworkCheckReachabilityByName(hostName, &flags) && flags > 0) {
  NSLog(@"Host is reachable: %d", flags);
}
else {
  NSLog(@"Host is unreachable");
}

Note: SystemConfiguration.framework is required

Upvotes: -8

Related Questions