Converting JSON and building a Dictionary using Objective C

Question

I have a very complex JSON data. And I tried to parse using objective c programming. The JSON data looks like the following (Here, I presented the simple format to explain. But it has very deep leveling):

{
    "university": "CUNY",
    "results": {
        "Engineering": 200,
        "Computer Science": 298,
        "Life Science": 28
    }
}

Using NSJSONSerialization, I tried to solve this and I use the following code:

NSDictionary *parsedObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:NULL];
[parsedObject objectForKey:@"results"];

And getting the result. But I need a dictionary like myResultDict which will be made form the results so that I can implement other functionality.

Can anybody give me a small hint how to do that?

Your second line retrieves the results dictionary, but doesn't do anything with it. You need to assign the result of that expression to a variable of type NSDictionary * — Paulw11
– Paulw11, Commented Jun 27, 2015 at 7:12
Got it! NSDictionary * = parsedObject objectForKey:@"results"]; :) — tiny_iOS_developer
– tiny_iOS_developer, Commented Jun 27, 2015 at 7:18
Also for something as potentially error-prone as this, don't miss the opportunity to trap and report errors (i.e. check parsedObject != nil and then report the error (which you have set to NULL). — Droppy
– Droppy, Commented Jun 27, 2015 at 8:32

Droppy · Accepted Answer · 2015-06-27 08:45:31Z

1

When you get the parsed data by using NSJSONSerialization it will give you parsed dictionary with multiple key-value pairs.

Then by fetching results key you can get your result dictionary.

For example:

NSDictionary *myResultDict = [parsedDictionary objectForKey:@"results"];

edited Jun 27, 2015 at 8:45

Droppy

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answered Jun 27, 2015 at 8:39

Abhishek Khedekar

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1 Comment

Droppy Over a year ago

Note: use objectForKey not valueForKey.

0yeoj · Accepted Answer · 2017-03-07 05:52:20Z

Try this method:

NSDictionary *dic = @{@"university": @"CUNY", @"results" : @{@"Engineering": @200, @"Computer Science": @298, @"Life Science": @28}};

[self getSubDictionaryWithDictionary:dic];

This method only logs the values inside NSDictionary, if you want to handle NSArray kind of class, up to you.. :)

- (void)getSubDictionaryWithDictionary:(NSDictionary *)dictionary
{
    for (id key in [dictionary allKeys])
    {
        id object = [dictionary objectForKey:key];

        NSLog(@"key:%@ value:%@",key, object);

        if ([object isKindOfClass:[NSDictionary class]])
        {
            [self getSubDictionaryWithDictionary:object];
        }  
    }
}

This extract all the dictionary inside the nested dictionary, you can modify it depending from what you need.. :)

Hope this is helpful.. Cheers.. :)

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