用Objective-c解析JSON？

Question

My goal is to parse pushshift.io's JSON using Objective-C. I have successfully fetched the JSON, but I receive an unrecognized selector sent to instance error when attempting to parse the text. How do I get the value for each key "author" , "author_flair_type" , etc, and turn that value into a string object?

Here is an example of the JSON:

{
    "data": [
        {
            "all_awardings": [],
            "author": "Le-Dragoon",
            "author_flair_css_class": null,
            "author_flair_richtext": [],
            "author_flair_type": "text"
        },
        {
            "all_awardings": [],
            "author": "Shiroi_Kage",
            "author_flair_css_class": null,
            "author_flair_richtext": [],
            "author_flair_text": null,
            "author_flair_type": "text"
        }
    ]
}

Here is the code I am using to fetch JSON from a URL:

int main(int argc, char *argv[], char *envp[]) {
    NSError *error;
    NSString *url_string = [NSString stringWithFormat: @"https://api.pushshift.io/reddit/search/submission/?sort_type=created_utc&subreddit=rasberry_pi"];
    NSData *data = [NSData dataWithContentsOfURL: [NSURL URLWithString:url_string]];
    NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];

    return 0;
}

Answer 1

The return value of JSONObjectWithData will likely be a dictionary, not an array. The object may contain an array. You could try something like:

     if (responseStatusCode == 200) {

         NSError* error;
         NSDictionary* json = [NSJSONSerialization
                               JSONObjectWithData:data //1
                               options:NSJSONReadingAllowFragments
                               error:&error];

         NSMutableArray *maAnimalsList = [[NSMutableArray alloc] init];

         for(id key in json) {

             [maAnimalsList addObject:key];
         }

     }

Answer 2

int main(int argc, char *argv[], char *envp[]) {
    NSError *error;
    NSString *url_string = [NSString stringWithFormat:@"https://api.pushshift.io/reddit/search/submission/?sort_type=created_utc&subreddit=rasberry_pi"];
    NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:url_string]];
    NSDictionary *result = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];

    if (error) {
        NSLog(@"error: %@", error);
        return 1;
    }

    NSArray *entities = result.allValues.firstObject;

    for (NSDictionary *dict in entities) {
        NSLog(@"author: %@, author_flair_type: %@", dict[@"author"], dict[@"author_flair_type"]);
    }

    return 0;
}

BTW, you should aware that the dataWithContentsOfURL method is synchronized network operation.