iOS Reachability Not Recognizing When Host is Removed

Question

I am building an application and trying to check and see if a device is still available on the network (by connecting to the devices IPAddress). I am using reachability to confirm that it is available.

When I network access for the iOS device (turn on airplane mode for example) everything works properly, but if I remove the device from the network, reachability does not seem to notice the change.

It seems like reachability is caching the results, and not seeing the update.

Please check your NSNotification observer. If it is getting removed while going into Background or coming to foreground. — Anil Gupta, Jun 01 '17 at 08:45
You can check apple Reachabilty sample class: https://developer.apple.com/library/content/samplecode/Reachability/Listings/Reachability_Reachability_h.html — Anil Gupta, Jun 01 '17 at 08:46

score 2 · Accepted Answer · edited Dec 19 '11 at 14:22

2

Don't use reachability then!

Use this bit of code instead which works a treat;

NSString *connected = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://www.google.com"]];
wait(25000);
if (connected == NULL) {

NSLog(@"Not Connected"); 
//Code to show if not connected

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@"Oops! You aren't connected to the Internet." 
delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
[alert release];

} else {
NSLog(@"Connected Successfully!");
//Any other code for successful connection
}

edited Dec 19 '11 at 14:22

Bill the Lizard

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answered Aug 10 '11 at 19:27

pixelbitlabs

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I was having the same issue with Nathan. Your solution is simple but work any time! the only thing I want to add is to use the new stringWithContentsOfURL format. NSError* error = nil; NSString *connected = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://twitter.com"] encoding:NSASCIIStringEncoding error:&error]; – user523234 Nov 01 '11 at 02:23
2

I would stay away from waiting 25 seconds to allow for the result to return. – burtlo Jan 12 '12 at 23:30

score 2 · Answer 2 · answered Aug 10 '11 at 19:29

2

The SCReachability API only checks if the local hardware is configured such that it could reach the specified address; it does not actually attempt to reach it. To determine if the target is alive and kicking, you must attempt to open a connection to it.

answered Aug 10 '11 at 19:29

Jonathan Grynspan

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score 1 · Answer 3 · edited May 23 '17 at 12:20

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Check out this answer. While the pixelbit's answer is viable, burtlo is right to bring up that just waiting 25 seconds isn't a great idea. Using the NSURLConnection is much cleaner.

edited May 23 '17 at 12:20

Community

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answered Jan 27 '12 at 10:51

scone

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score 0 · Answer 4 · answered Jun 01 '17 at 08:50

0

Apple updated the Reachabilty class file. You can test it with latest Xcode. here is link: Apple Reachabilty Sample Code

I tested with Xcode 8.3.1 on iPhone 6 version 10.3.1. It will notify user for change in network status.

answered Jun 01 '17 at 08:50

Anil Gupta

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iOS Reachability Not Recognizing When Host is Removed

4 Answers4

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