http://google.com NOT working for Internet Connection Detection

[marshusensei]

My new app just released today and it appears that google.com is no longer working for my Internet Connection detection:

            //check for Internet Connection
            NSURL *url = [[NSURL alloc] initWithString:@"http://google.com"];
            NSError *error = nil;
            NSStringEncoding encoding;
            
            NSString *my_string = [[NSString alloc] initWithContentsOfURL:url
                                                             usedEncoding:&encoding 
                                   
                                                                    error:&error];
            
            //if no connection
            
            if ([my_string length] == 0) {
                UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"No Internet Connection" message:@"A connection to the Internet is required to access this page." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
                
                [alertView show];
                
            }

Is anyone else experiencing this issue? All other URLs still work.

[Domele]

That isn't a good way to check for an internet connection. I think one reason is if the server hangs, your app freezes. Here is the advised way: objective c - How to check for an active Internet Connection on iPhone SDK? - Stack Overflow

[marshusensei]

Thanks Domele. I was ignorant to this. I'll switch to reachability in the next update.

[sneaky]

Reachability is not fool proof either btw.
This may have changed with late revisions of reachability but last time I used it it was only able to detect if you had a network connection, not if you had internet.

Say you're at a hotel, you connect to the hotel wifi - you are properly connected to the network but whatever url you type in you are directed to a landing page for you to type in your room number.

This type of connection will show up as perfectly OK in reachability and your app goes off to do whatever but will fail (depending on how you handle it...)

Same thing if you are on a network with 'pre-pay' - the user could be out of credit. The phone is perfectly connected to 3g but can't get any data through. Reachability will however report that the connection is OK.


What you probably want to do is first check reachability - if you have a OK there you can try to download a very small file from your own server. If that works then you can assume connectivity for a small bit of time.

Testing google.com probably doesn't make any sense if you want to connect to a service you have running on your own server. You should test the actual server you are trying to use.

The other thing is that connectivity can come and go. The user could be in a car and have very good service at one point but a few minutes later have no service. So make sure you properly implement the reachability notifications.

[ckgni]

Reachability had lots of bugs for me.

The most trustworthy method I use in my apps and being accepted by Apple, is adding in my viewcontroler .m files this:

-(void)webView:(UIWebView *)webview didFailLoadWithError:(NSError *)error {
    UIAlertView *erroralert = [[UIAlertView alloc] initWithTitle:@"Error" 
                                                         message:@"No Internet connection. This application requires an Internet connection to function properly."
                                                        delegate:nil 
                                               cancelButtonTitle:@"Close" 
                                               otherButtonTitles: nil];
    [erroralert show];
    
}

This displays a popup alert with a message that there is no active Internet connection.

You can add this code in your viewcontroller m files, just after all the #import and @synthesize commands.

Replace "webview" with the name of your UIWebView.

[baja_yu]

Originally Posted by sneaky

Reachability is not fool proof either btw.
This may have changed with late revisions of reachability but last time I used it it was only able to detect if you had a network connection, not if you had internet.

Yes but Reachability has methods for checking connection to a particular host name or IP address, not just network connection in general.

[sneaky]

Originally Posted by baja_yu

Yes but Reachability has methods for checking connection to a particular host name or IP address, not just network connection in general.

I stand corrected:

//reachabilityWithHostName- Use to check the reachability of a particular host name. 

+ (Reachability*) reachabilityWithHostName: (NSString*) hostName;

 

//reachabilityWithAddress- Use to check the reachability of a particular IP address. 

+ (Reachability*) reachabilityWithAddress: (const struct sockaddr_in*) hostAddress;

 

//reachabilityForInternetConnection- checks whether the default route is available.  

//  Should be used by applications that do not connect to a particular host

+ (Reachability*) reachabilityForInternetConnection;

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