How to handle network or server error?

Question

I am using the following code

NSMutableArray *image=[[NSMutableArray alloc]init];
    for(int i=1;i<4;i++)
    {
        NSString *urlString =[NSString stringWithFormat:@"http://www.isco.com/webproductimages/appBnr/bnr%d.jpg",i];
        NSData *photoData = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]];
       [image addObject:photoData];
    }

my problem is, if the network failure occurs, it shows thread... How to handle this thread??

score 0 · Answer 1 · answered Sep 21 '12 at 12:56

    NSMutableArray *image=[[NSMutableArray alloc]init];
        for(int i=1;i<4;i++)
        {
            NSString *urlString =[NSString stringWithFormat:@"http://www.isco.com/webproductimages/appBnr/bnr%d.jpg",i];

         NSError *error;
     NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString] options:NSDataReadingUncached error:&error    ];

        if (data) {
      [image addObject:photoData];
         }
        else{
            if (error) {
                NSLog(error);
            }
        }


  }

score 0 · Accepted Answer · edited May 23 '17 at 10:25

Your "thread" problem (it is a error/exception) could be caused by multiple factor. It could be that the internet connection is down, or the server throw some form of http error.

To start of, make sure you are not losing any internet connection when running network operations. There are number of advice on how to check for internet connection. One is to use the Reachability class provided by the SDK itself. Look at this article on how to do so: How to check for an active Internet connection on iOS or OSX?

This article here would give you further insights on internet connection as well: Testing internet connection on iPad app using ios5

When you determined that it is not the internet connection, but a http server error. Make sure the http service you are calling is passing back the data properly. I use some REST client tools to check for this (REST Client)

Finally, I tested out the URL you are trying to call on a browser, it throws a Bad Request error. Meaning it have nothing to do with your iOS code. If this server is under your control, you should fix that.

How to handle network or server error?

2 Answers2