Possible bug in CFNetDiagnosticCopyNetworkStatusPassively? Returning kCFNetDiagnosticConnectionDown over 3G/4G only.

Question

Got a weird bug here. This only manifests when the iOS Device is being used exclusively on 3G/4G networks. i.e. if over WiFi - no bug and it all works fine.

- ( BOOL ) isInternetAccessAvailable
{
    CFNetDiagnosticRef diag;

    diag = CFNetDiagnosticCreateWithURL ( NULL, ( __bridge  CFURLRef )[NSURL URLWithString:@"www.apple.com"] );

    CFNetDiagnosticStatus status;

    status = CFNetDiagnosticCopyNetworkStatusPassively ( diag, NULL );

    CFRelease ( diag );

    if ( status == kCFNetDiagnosticConnectionUp )
    {
        return YES;
    }
    else
    {
        NSString * title   = @"No Internet Connection";
        NSString * message = @"Please ensure you have an Internet Connection.";

        [self showAlertWithTitle:title andMessage:message];

        return NO;
    }
}

Okay, so I have the above method that gets called before I try and load data into a UIWebView.

As I said - over a WiFi network, this works perfectly.

If WiFi is turned off (or unavailable / not connected) and the device is using a SIM for 3G/4G networks.

the line where is calls:

status = CFNetDiagnosticCopyNetworkStatusPassively ( diag, NULL );

returns a long equivalent to:

kCFNetDiagnosticConnectionDown

So therefore my test fails and I display a warning UIAlertView to the user.

But the network is there! If I change the test line to this:

if ( ( status == kCFNetDiagnosticConnectionUp ) || ( status == kCFNetDiagnosticConnectionDown ) )

It works over 3G/4G and downloads the web page - so the device or network isn't at fault.

But the call to CFNetDiagnosticCopyNetworkStatusPassively is failing only on 3G/4G.

Any ideas?

This has just been found in an app I recently expedited into the App Store to meet advertising and merchandising deadlines and if there is a fault in my code - I need this fixed and resubmitted asap.

Answer 1

Confirmed bug by Apple.

Dupe if you want: Bug ID# 12443370

Answer 2

You can use this to check connexion

How to check for an active Internet connection on iOS or OSX?.

cannyboyn answer for synchronous version : Take Reachability.h and Reachability.m in https://github.com/tonymillion/Reachability

#import "Reachability.h"

- (BOOL)connected 
{
    Reachability *reachability = [Reachability reachabilityForInternetConnection];  
    NetworkStatus networkStatus = [reachability currentReachabilityStatus]; 
    return !(networkStatus == NotReachable);
}