Question

I’ve been developing app, that makes asynchronous requests for JSON type of data. Lately, I found strange bug in my code and I can’t tell why it is happening.

Ok to the code!

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

NSError *error=nil;

    result = [NSJSONSerialization JSONObjectWithData:retrievedData options:kNilOptions error:&error];
        NSLog(@"Result %@",result);
        NSLog(@"Retrieved data %@",retrievedData);
}

Result is NSDictionary, retrievedData is NSMutableData.
99% of the time, it works fine, connectionDidFinishLoading gets called, and my result is populated. However, in that 1% of the time retrieved data is filled with data, but my result is null.(as you can see on the picture. Could anyone help me please?

Edit: I get following error

Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (Garbage at end.) UserInfo=0x753e5c0 {NSDebugDescription=Garbage at end.}

Answer 1

It would help if you take a look at the error first, to see if that gives any indication of what is wrong.

[edit]
Your error mentions the reason: Garbage at end..

The response from the webserver is not valid JSON, it contains invalid characters at the end of the output.