help me to parse JSON value using JSONTouch

Question

I have the following json:

http://www.adityaherlambang.me/webservice.php?user=2&num=10&format=json

I would like to get all the name in this data by the following code, but it gives an error. How can I fix it?

NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];


 NSDictionary *results = [responseString JSONValue];

 NSDictionary *users = [results objectForKey:@"users"] objectForKey:@"user"];


 for (NSDictionary *user in users){
  //NSLog(@"key:%@, value:%@", user, [user objectForKey:user]);
  NSString *title = [users objectForKey:@"NAME"];
  NSLog(@"%@", title);
 }

Error:

2011-01-29 00:18:50.386 NeighborMe[7763:207] -[__NSArrayM objectForKey:]: unrecognized selector sent to instance 0xb618840
2011-01-29 00:18:50.388 NeighborMe[7763:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM objectForKey:]: unrecognized selector sent to instance 0xb618840'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x027d9b99 __exceptionPreprocess + 185
    1   libobjc.A.dylib                     0x0292940e objc_exception_throw + 47
    2   CoreFoundation                      0x027db6ab -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
    3   CoreFoundation                      0x0274b2b6 ___forwarding___ + 966
    4   CoreFoundation                      0x0274ae72 _CF_forwarding_prep_0 + 50
    5   NeighborMe                          0x0000bd75 -[NeighborListViewController connectionDidFinishLoading:] + 226
    6   Foundation                          0x0007cb96 -[NSURLConnection(NSURLConnectionReallyInternal) sendDidFinishLoading] + 108
    7   Foundation                          0x0007caef _NSURLConnectionDidFinishLoading + 133
    8   CFNetwork                           0x02d8d72f _ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE + 285
    9   CFNetwork                           0x02e58fcf _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 389
    10  CFNetwork                           0x02e5944b _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 1537
    11  CFNetwork                           0x02d82968 _ZN19URLConnectionClient13processEventsEv + 100
    12  CFNetwork                           0x02d827e5 _ZN17MultiplexerSource7performEv + 251
    13  CoreFoundation                      0x027bafaf __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
    14  CoreFoundation                      0x0271939b __CFRunLoopDoSources0 + 571
    15  CoreFoundation                      0x02718896 __CFRunLoopRun + 470
    16  CoreFoundation                      0x02718350 CFRunLoopRunSpecific + 208
    17  CoreFoundation                      0x02718271 CFRunLoopRunInMode + 97
    18  GraphicsServices                    0x030b800c GSEventRunModal + 217
    19  GraphicsServices                    0x030b80d1 GSEventRun + 115
    20  UIKit                               0x002e9af2 UIApplicationMain + 1160
    21  NeighborMe                          0x00001c34 main + 102
    22  NeighborMe                          0x00001bc5 start + 53
    23  ???                                 0x00000001 0x0 + 1
)
terminate called after throwing an instance of 'NSException'

I really just wanted to be able to iterate through the names

Answer 1

NSDictionary *results = [responseString JSONValue];

NSDictionary *users = [results objectForKey:@"users"] objectForKey:@"user"];

1. The JSON data has an array as its top level value. It’s not a JSON object, hence it’s not a dictionary. This is why you get the -[__NSArrayM objectForKey:]: unrecognized selector sent to instance exception.
2. There is no "users" entry in your JSON data.
3. The code above doesn’t compile.

---

The first step is to understand your JSON data. It is structured as follows:

1. the top level value is an array
2. each element in the array is an object/dictionary with a single key called "user"
3. the value of the "user" key is itself another object/dictionary with various key-value pairs

If you want to iterate over the users and print the value for the "NAME" key, follow the example below.

NSString *responseString = [[NSString alloc] initWithData:responseData
    encoding:NSUTF8StringEncoding];

// 1. the top level value is an array
NSArray *results = [responseString JSONValue];

// 2. each element in the array is an object/dictionary with
// a single key called "user"
for (NSDictionary *element in results) {
    // 3. the value of the "user" key is itself another object/dictionary
    // with various key-value pairs
    NSDictionary *user = [element objectForKey:@"user"];
    NSString *title = [user objectForKey:@"NAME"];
    NSLog(@"%@", title);
}

Answer 2

It seems to me that when you create the "users" dictionary you are actually creating a "user" dictionary.

 NSDictionary *users = [[results objectForKey:@"users"] objectForKey:@"user"];//crating users dictionary with 1 "user" inside.

EDIT

in second view. why don't you just iterate the "result" dictionary? like that -

 for (NSDictionary *user in result){
  //NSLog(@"key:%@, value:%@", user, [user objectForKey:user]);
  NSString *title = [users objectForKey:@"NAME"];
  NSLog(@"%@", title);
 }

hope it will help shani