Array returned from SBJSON parser is invalid (iOS)

I am running into an error using SBJSON parser on a response string returned from a PHP webservice:

NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];

NSError *error;
SBJSON *json = [SBJSON new];
NSArray *returnedFromWeb = [json objectWithString:responseString error:&error];

[articles_parsed removeAllObjects];

for (int i = 0; i < [returnedFromWeb count]; i++) 
{
    NSDictionary *dictColumns = [returnedFromWeb objectAtIndex:i];
    [self parseArticlesObject:dictColumns];
    dictColumns = nil;
}

I receive an unrecognized selector sent to instance error on the objectAtIndex call above. When I check the values contained in my array (returnedFromWeb), it shows that there are 17 objects. However, inspecting each object shows the following error:

(<invalid>) [0] = <error: expected ']' error: 1 errors parsing expression >

I have posted below the data returned from the SBJSON parser for the object at index [0] below:

{
    0 =     {
        author = "CCJ Staff";
        category1 = Products;
        excerpt = "Toyo";
        modified = "2014-03-25 08:33:57";
        "short_link" = "http://www.example.com/?p=95326";
        thumbnail = "http://www.example.com/files/2014/03/ Tire.jpg";
        "thumbnail_243x243" =     "http://www.example.com/ihz.php?src=/blogs.dir/10/files/2014/03/ Tire.jpg&amp;w=243&amp;h=243&amp;q=100&amp;zc=1";
        title = "medium-duty";
    };

And here is the string that is being parsed by SBJSON (shortened to contain only the first object, the comma at the end is where the next object would begin):

{"numberposts":240,"tax_query":[{"taxonomy":"topic","terms":[75,43550,14394,16564,1795,43,22,12950],"field":"term_id","orderby":"date","order":"DESC"}],"0":{"title":"medium-duty","category1":"Products", excerpt":"Toyo","modified":"2014-03-25 08:33:57","author":"Staff","thumbnail":"http://www.ccjdigital.com/files/2014/03/Tire.jpg","short_link":"http://www.ccjdigital.com/?p=95326"},

Any help is appreciated! I am fairly new to iOS and SBJSON, and have not been able to figure out why my array is invalid.

Solution

My first thought is that you're getting an NSDictionary back not an NSArray. To find out add a breakpoint before you call objectAtIndex on the returned item, and in the debugger at the bottom of the screen type: po [returnedFromWeb class]

This will tell you the actual class of the returned object. I say that it might be a dictionary because the JSON you pasted in starts with a { (curly brace) where an array would start with [

Since you can't always guarantee that the JSOn will be formatted to be an array or a dictionary you can do some testing to see if it responds to the objectAtIndex: method, as an example, which would indicate it's an NSArray.

id *returnedFromWeb = [json objectWithString:responseString error:&error];
if ([returnedFromWeb respondsToSelector:@selector(objectAtIndex:)]) {
  //it's an array do array things.
} else {
  //it's a dictionary do dictionary things.
}

Hope that helps!