Question

I am trying to make my iPhone app more robust, by ensuring that it doesn’t crash when there is no network connection. Right now the app attempts to make a connection on startup immediately, through the app delegate. It has no issues if wifi or cellular is available, but it will crash if there is no network connection visible. I have looked around on this site and haven’t found anything that quite fits my problem. I have the feeling it should be just a simple line of code, like an objective-c equivalent of a pseudo- ‘isConnection’, or something similar:

if (isConnection) {
    - sendSynchronousRequest for json data I'm using
    - manipulate the data, etc., and continue with normal operations
} else {
    - send an output message to a view controller, 
      letting the user know what's wrong.
}

I can’t seem to isolate the (admittedly abstract) “isConnection” condition that I’m looking for, specifically. Does anyone have experience or advice with this topic?

Answer 1

The reachability class is very easy to use. Download the class files here https://developer.apple.com/library/ios/#samplecode/Reachability/Introduction/Intro.html

You also need to add the SystemConfiguration.framework

Here’s the code you need:

-(BOOL)isConnection {
    Reachability *reach = [Reachability reachabilityWithHostName:@"www.google.com"];
    //replace www.google.com with your own host you're checking for
    NetworkStatus hostStatus = [reach currentReachabilityStatus];
    if (hostStatus != NotReachable) {
        //There are also other status enums like
        //ReachableViaWiFi
        //ReachableViaWWAN (3G/LTE)
        //if you need to detect if user is on cellular, act accordingly
        return YES;
    }
    return NO;
}

Then you can call your method:

if ([self isConnection]) {
    //do something
} else {
    //no connection, inform user
}