A quick a dirty JSON example using Objective C (requires clean up and refactoring of the code into better methods). This code goes to one of my VPS's that has Tiny Tiny RSS running. The example shows you how to log into the system, then extract the categories necessary. Code that has been mashed together from : iOS6 Cookbook and http://www.raywe…

gistfile1.m

//
//  ViewController.m
//  JSONExample
//
//  Created by Kenny on 2013-05-08.
//  Copyright (c) 2013 tkee.org. All rights reserved.
//

#import "ViewController.h"

#define kTinyTinyRSSURL [NSString stringWithFormat:@"http://dev.tkee.org/tt-rss/api/"]

@interface ViewController ()

@end

@implementation ViewController

- (void)fetchData:(NSMutableDictionary *)dictionary
{
    NSError *error = nil;
    NSData *jsonData = [NSJSONSerialization
                        dataWithJSONObject:dictionary options:NSJSONWritingPrettyPrinted error:&error];
    
    
    if ([jsonData length] > 0 && error == nil){
        NSLog(@"Successfully serialized the dictionary into data."); NSString *jsonString =
        [[NSString alloc] initWithData:jsonData
                              encoding:NSUTF8StringEncoding];
        NSLog(@"JSON String = %@", jsonString);
        
        
        // create the connection and send it to the server
        NSString *requestString = kTinyTinyRSSURL;
        
        NSURL *url = [NSURL URLWithString:requestString];
        
        NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url];
        [req setHTTPMethod:@"POST"];
        
        NSString *dataString = jsonString;
        
        NSData *requestData = [NSData dataWithBytes:[dataString UTF8String] length:[dataString length]];
        
        [req setHTTPBody:requestData];
        
        NSURLResponse *theResponse = NULL;
        NSError *theError = NULL;
        NSData *theResponseData = [NSURLConnection sendSynchronousRequest:req returningResponse:&theResponse error:&theError];
        
        
        //deserialize the response into something usable
        NSDictionary* json = [NSJSONSerialization
                              JSONObjectWithData:theResponseData //1
                              options:kNilOptions
                              error:&error];
        
        NSArray* validResponse = [json objectForKey:@"content"]; //2
        NSLog(@"content: %@", validResponse); //3
        // TODO: need to refactor into something like fetchData
        if ([_sid length] == 0) {
            _sid = [(NSDictionary*)[json objectForKey:@"content"] objectForKey:@"session_id"];
            NSLog(@"sid: %@", _sid);            
        }
        
    }
    else if ([jsonData length] == 0 && error == nil){
        NSLog(@"No data was returned after serialization.");
    }
    else if (error != nil){
        NSLog(@"An error happened = %@", error);
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    NSString *login = @"demo";;
    NSString *password = @"Pa$$w0rdForD3m0";
    NSLog(@"Username: %@", login);
    NSLog(@"Password: %@", password);
    
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithDictionary:@{
                                       @"op" : @"login", @"user" : login, @"password" : password
                                       }];
    
    [self fetchData:dictionary];
    [self getCategories:_sid];
    
}


- (void) getCategories:(NSString *)sid {
    
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithDictionary:@{
                                       @"sid" : sid, @"op" : @"getCategories"
                                       }];
    
    [self fetchData:dictionary];
    
    
}


- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

gistfile2.m

//
//  ViewController.h
//  JSONExample
//
//  Created by Kenny on 2013-05-08.
//  Copyright (c) 2013 tkee.org. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@property (strong, nonatomic) NSString *sid;
@property (strong, nonatomic) NSDictionary *json;

- (void)getCategories:(NSString *)sid;
- (NSDictionary*)fetchedData:(NSMutableDictionary *)dictionaryJSON;

@end

gistfile3.txt

2013-05-08 14:27:19.334 JSONExample[7976:c07] Successfully serialized the dictionary into data.
2013-05-08 14:27:19.334 JSONExample[7976:c07] JSON String = {
  "op" : "login",
  "user" : "yourUser",
  "password" : "yourPassword"
}
2013-05-08 14:27:19.496 JSONExample[7976:c07] content: {
    "api_level" = 5;
    "session_id" = kbgfb44dcctp9kouabi3ql6874;
}
2013-05-08 14:27:19.496 JSONExample[7976:c07] sid: kbgfb44dcctp9kouabi3ql6874
2013-05-08 14:27:26.648 JSONExample[7976:c07] Successfully serialized the dictionary into data.
2013-05-08 14:27:26.648 JSONExample[7976:c07] JSON String = {
  "sid" : "kbgfb44dcctp9kouabi3ql6874",
  "op" : "getCategories"
}
2013-05-08 14:27:26.766 JSONExample[7976:c07] content: (
        {
        id = 23;
        "order_id" = 0;
        title = Technology;
        unread = 50;
    },
        {
        id = 24;
        "order_id" = 0;
        title = News;
        unread = 15;
    },
        {
        id = "-1";
        title = Special;
        unread = 65;
    },
        {
        id = 0;
        title = Uncategorized;
        unread = 0;
    }
)