Question

I’m returning JSON with a rough structure like the one below, and I’m trying to figure out how I can count how many platforms there are (in this case, three, but could be anything from 1 to 20 or so). I’ve returned the JSON into an NSDictionary and am using lines such as these to retrieve the data I need:

_firstLabel.text = _gameDetailDictionary[@"results"][@"name"];

In the above case, it’ll grab the name from the results section. Since there are multiple platforms, I need to construct a loop to cycle through each name inside the platforms section. Not too sure how to go about that. All help appreciated!

"results":{
    "platforms":[
        {
            "api_detail_url":"http://",
            "site_detail_url":"http://",
            "id":18,
            "name":"First Name"
        },
        {
            "api_detail_url":"http://",
            "site_detail_url":"http://",
            "id":116,
            "name":"Second Name"
        },
        {
            "api_detail_url":"http://",
            "site_detail_url":"http://",
            "id":22,
            "name":"Third Name"
        }
    ],

EDIT: Here’s my fetchJSON method:

- (NSDictionary *) fetchJSONDetail: (NSString *) detailGBID {

    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible: YES];

    NSString *preparedDetailURLString = [NSString stringWithFormat:@"http://whatever/format=json", detailGBID];
    NSLog(@"Doing a detailed search for game ID %@", detailGBID);

    NSData *jsonData = [NSData dataWithContentsOfURL: [NSURL URLWithString:preparedDetailURLString]];

    _resultsOfSearch = [[NSDictionary alloc] init];
    if (jsonData) {
        _resultsOfSearch = [NSJSONSerialization JSONObjectWithData: jsonData
                                                           options: NSJSONReadingMutableContainers
                                                             error: nil];
    }

    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible: NO];

    NSString *results = _resultsOfSearch[@"number_of_page_results"];
    _numberOfSearchResults = [results intValue];

    NSArray *platforms = [_resultsOfSearch valueForKey:@"platforms"];
    int platformsCount = [platforms count];
    NSLog(@"This game has %d platforms!", platformsCount);

    return _resultsOfSearch;

}

Answer 1

The “platforms” JSON field is an array, so assuming you’ve de-serialised the JSON using something like,

NSMutableDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:resultsData options:NSJSONReadingMutableContainers error:&error];

Then, you can assign platforms to an NSArray,

NSDictionary *results = [responseJSON valueForKey:@"results"];

NSArray *platforms = [results valueForKey:@"platforms"];

…and find the number of platforms via,

int platformsCount = [platforms count];

In your case, where you want to iterate through the platforms, you can use,

for (NSDictionary *platform in platforms)
{
    // do something for each platform
}