I don't understand how to use the JSON data in Xcode - objective-c

Question

I have successfully downloaded and parsed (I think) the JSON data
NSURL *quoteURL = [NSURL URLWithString:#"http://www.qwoatzz.com"];
NSData *jsonData = [NSData dataWithContentsOfURL:quoteURL];
NSError *error = nil;
NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];
However, I'm not too sure how to actually use the JSON data. If the JSON file has an array with two keys, how do I get a value from one of these keys at a specific index (the first one for example) and use that to change the text of a label (I know how to do that, it's just the JSON part I am stuck on)?
2014-10-20 19:46:10.616 Qwoatz-2[3147:454481] dataDictionary : {
count = 10;
"count_total" = 1871;
pages = 188;
posts = (
{
author = "Jason Seifer";
date = "2014-10-20 13:54:11";
id = 24317;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/1634685862_92b26b9167_o-150x150.jpg";
title = "What Employers Are Looking For in a Junior Rails Developer";
url = "http://blog.teamtreehouse.com/employers-looking-junior-rails-developer";
},
{
author = "Zac Gordon";
date = "2014-10-16 09:27:38";
id = 24296;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/brochure-site-150x150.png";
title = "When is WordPress.com the Right Solution?";
url = "http://blog.teamtreehouse.com/wordpress-com-right-solution-website";
},
{
author = "Gill Carson";
date = "2014-10-15 12:52:43";
id = 24287;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/Tahoe_team-Photo-150x150.jpg";
title = "We Are Family – The Whole Team!";
url = "http://blog.teamtreehouse.com/family";
},
{
author = "Jason Seifer";
date = "2014-10-14 15:26:11";
id = 24292;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/Chartist-Simple-responsive-charts-2014-10-14-15-24-43-150x150.jpg";
title = "Responsive Charts";
url = "http://blog.teamtreehouse.com/responsive-charts";
},
{
author = "Guil Hernandez";
date = "2014-10-13 09:28:05";
id = 24228;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/09/blend-mode-mult-150x150.jpg";
title = "Cutting-Edge CSS Features You Can Use Today";
url = "http://blog.teamtreehouse.com/cutting-edge-css-features-can-use-today";
},
{
author = "Faye Bridge";
date = "2014-10-10 09:00:45";
id = 24230;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/09/Nick-Bryan-150x150.jpg";
title = "After Just 6 Months Learning Nick is a full-time Web Developer";
url = "http://blog.teamtreehouse.com/6-months-nick-now-full-time-web-developer-major-computing-firm";
},
{
author = "Pasan Premaratne";
date = "2014-10-09 13:59:23";
id = 24250;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/Screen-Shot-2014-10-06-at-5.57.16-PM-150x150.png";
title = "Making a Network Request in Swift";
url = "http://blog.teamtreehouse.com/making-network-request-swift";
},
{
author = "Zac Gordon";
date = "2014-10-09 09:21:29";
id = 24278;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/wordpress_themes-150x150.jpg";
title = "New Course: WordPress Theme Development";
url = "http://blog.teamtreehouse.com/new-course-wordpress-theme-development";
},
{
author = "Dave McFarland";
date = "2014-10-08 13:47:55";
id = 24255;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/Screen-Shot-2014-10-06-at-1.02.40-PM-150x150.png";
title = "How to Install Node.js and NPM on a Mac";
url = "http://blog.teamtreehouse.com/install-node-js-npm-mac";
},
{
author = "Jason Seifer";
date = "2014-10-07 16:15:00";
id = 24273;
thumbnail = "http://blog.teamtreehouse.com/wp-content/uploads/2014/10/html5-device-mockups-150x150.jpg";
title = "Device Mockups";
url = "http://blog.teamtreehouse.com/device-mockups";
}
);
status = ok;
}
An example JSON file that was parsed.

Answer 1

Loop through the dictionary:
for(NSString *key in dataDictionary) {
id myObject = [dataDictionary objectForKey:key];
//do something with myObject
}
An NSDictionary is not an ordered collection, so there is no guarantee that looping through a dictionary as shown above will always loop through the keys in the same order. Apple doesn't provide an ordered dictionary with Cocoa/Cocoa Touch, and generally it is a bad idea to subclass NSDictionary or NSMutableDictionary as they are part of a class cluster.
Looking at the text from your example, posts is actually an array full of dictionaries. Assuming all the keys in your example are constant across the JSON files that you will be fetching, you could retrieve it using
NSArray *posts = [dataDictionary arrayForKey:#"posts"];
This array already appears to be ordered by date. You could then get the title for each post
for(int i = 0; i < [posts count]; i++) {
NSString *title = [((NSDictionary *)(posts[i])) objectForKey:#"title"];
//do something with title
}

Answer 2

1) Do you know the data is an array?
the JSON file has an array with two keys,...
value from one of these keys at a specific index...
This is somewhat of a mixed metaphor for me. When I have a JSON Array or NSArray, I tend to only think of indices (since that how arrays are ordered), and when I have JSON Objects or NSDictionaries, I tend to think of keys.
So, does the return value look like this:
[ "cat", 1, "a" ]
or does the data look like this:
{
"cat": {
"count": 1,
"tag": "a"
}
}
The first example is an Array with 3 elements; the second is an Object with 1 member that itself has 2 members.
2) If the data is correctly parsed as either an NSArray, or NSDictionary ...
Then you simply need to extract the data you want, with the accessors available on either container.
E.g.
NSArray *a = ...
[a firstObject];
[a objectAtIndex:0]; // same as above
NSDictionary *d = ...
d[#"memberName"];
[d objectForKey:#"memberName"]; // same as above
You'll want to actually save that data, or pass it to be processed, instead of just invoking the accessor.
UPDATE: based on the example data updated in the question.
One method is that you could extract the data both a bit manually, and iteratively.
NSDictionary *dataDictionary = ...
NSInteger count = [[dataDictionary objectForKey:#"count"] integerValue];
NSInteger countTotal = [[dataDictionary objectForKey:#"count_total"] integerValue];
NSInteger pagesCount = [[dataDictionary objectForKey:#"pages"] integerValue];
NSString *status = [dataDictionary objectForKey:#"status"];
NSArray *posts = [dataDictionary objectForKey:#"posts"];
for (NSDictionary *post in posts) {
for (NSString *key in post) {
NSLog(#"%#: %#", key, post[key]);
}
}
When you log dataDictionary, unquoted elements that are clearly strings are strings, elements in quotes are strings, integers and other numbers are likely usable numbers, but they may be strings (depends on return format), the date will be a string (and you can use NSDate and NSDateFormatter to pretty print it), status is just a string; for posts, the '(' and ')' wrap an array, and '{','}' wrap dictionaries.
UPDATE 2:
If you really want to do advanced searching, you can use NSPredicate to filter NSDictionary's or NSArray's. For example, something like the following would work:
#import <Foundation/Foundation.h>
int main(int argc, char *argv[]) {
#autoreleasepool {
NSDictionary *data = #{
#"stuff": #1,
#"posts": #[
#{ #"id": #1, #"title": #"one" },
#{ #"id": #2, #"title": #"two" },
#{ #"id": #3, #"title": #"three" },
#{ #"id": #4, #"title": #"four" },
#{ #"id": #5, #"title": #"five" },
]
};
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF.id == %#", #4];
NSString *title = [[data[#"posts"] filteredArrayUsingPredicate:predicate] firstObject];
NSLog(#"title: %#", title);
}
}
prints
title: {
id = 4;
title = four;
}

Answer 3

You can use JSONModel Framework
JSONModel is a data model framework for iOS and OSX. It's written in Objective-C and helps you in several different ways.
You can read more about its key features below:
Rapidly write model code
Validation of the model's input
Atomic data
Type casting between JSON and Obj-C
Built-in data transformers
Custom data transformers
Model cascading
Convert back & forth from/to JSON
Persist model state in memory or file
Create models straight from the Internet
Automatic model compare methods
Note Please make sure your properties name match with key name in JSON
JSONModel Framework
GitHub Link