How to iterate through a simple JSON object in Objective-C?

Question

I'm very new to Objective-C, I'm a hardcore Java and Python veteran.

I've created an Objective-C script that calls a URL and gets the JSON object returned by the URL:

// Prepare the link that is going to be used on the GET request
NSURL * url = [[NSURL alloc] initWithString:@"http://domfa.de/google_nice/-122x1561692/37x4451198/"];

// Prepare the request object
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url
                                            cachePolicy:NSURLRequestReturnCacheDataElseLoad
                                        timeoutInterval:30];

// Prepare the variables for the JSON response
NSData *urlData;
NSURLResponse *response;
NSError *error;

// Make synchronous request
urlData = [NSURLConnection sendSynchronousRequest:urlRequest
                                returningResponse:&response
                                            error:&error];

// Construct a Array around the Data from the response
NSArray* object = [NSJSONSerialization
                   JSONObjectWithData:urlData
                   options:0
                   error:&error];


//NSLog(object);
// Iterate through the object and print desired results

I've gotten this far:

NSString* myString = [@([object count]) stringValue];

NSLog(myString);

Which returns the size of this array, but how can I loop through this JSON object and print each element?

Here's the JSON I'm loading:

{
    "country": "United States",
    "sublocality_level_1": "",
    "neighborhood": "University South",
    "administrative_area_level_2": "Santa Clara County", 
    "administrative_area_level_1": "California",
    "locality": "City of Palo Alto",
    "administrative_area_level_3": "",
    "sublocality_level_2": "",
    "sublocality_level_3": "",
    "sublocality":""
}

Answer 1

The top-level object your JSON object is a dictionary, not an array, as indicated by the curly braces. If you are not sure whether you are going to get an array or a dictionary back, you can do some safety checking like this:

// Construct a collection object around the Data from the response
id collection = [NSJSONSerialization JSONObjectWithData:urlData
                                                options:0
                                                  error:&error];

if ( collection ) {
    if ( [collection isKindOfClass:[NSDictionary class]] ) {
        // do dictionary things
        for ( NSString *key in [collection allKeys] ) {
            NSLog(@"%@: %@", key, collection[key]);
        }
    }
    else if ( [collection isKindOfClass:[NSArray class]] ) {
        // do array things
        for ( id object in collection ) {
            NSLog(@"%@", object);
        }
    }
}
else {
    NSLog(@"Error serializing JSON: %@", error);
}