How to divide the date from JSON output? - iphone

I am developing one application.In that i use the json.Json gives the output and that output is stored in one dictionary like
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
[responseData release];
NSDictionary *results = [responseString JSONValue];
So my problem is how to separate the data from results.I want to print the only city name.so please tell me how to extract the data from dictionary.

you need to see the response and by using objectForKey: (method in NSDictionary) you can find what ever you want. (pick data by their key).

Check NSDictionary. Use objectForKey: to retrive the data. The key will be your tag value.

Related

parsing JSON response from server in same order in ios

i have an app which fetches JSON response from server. the JSON response from server looks as follows:
{"status":"SUCCESS","message":"XYZ","token":"ABCDEFGHIJ"}
now i need to store this in a NSDictionary for further parsing. so i use the following approach:
urldata1=[NSURLConnection sendSynchronousRequest:theRequest returningResponse:&res error:nil]; NSDictionary
*myDictionary=[NSJSONSerialization JSONObjectWithData:urldata1 options:NSJSONReadingMutableContainers error:nil];
}
but now the dictionary i get looks as follows:
{
message = "XYZ";
status = SUCCESS;
token = "ABCDEFGHIJ";
}
So i see that the dictionary has been sorted on the basis of keys... is there a way to reproduce the exact same response from server in my dictionary..
It doesn't matter in what order the NSDictionary is because you retrieve the object from the dictionary with keys.
So if you want to access the status first use this code
NSString *status = [myDictionary objectForKey#"status"];
NSString *message = [myDictionary objectForKey#"message"];
NSString *token = [myDictionary objectForKey#"token"];
And you can access a Dictionary inside a Dictionary like this
NSDictionary *dict= [myDictionary objectForKey#"SomeOtherDictionary"];
Sorting a dictionary is meaningless. You need to first create an array which will sort according to your needs.
You can refer Sorting NSDictionary from JSON for UITableView for further explanations.

Converting an NSArray of Dictionaries to JSON array in iOS

I need to send an NSArray to the server in the JSON array format. How can I convert it to JSON. This is a sample of my NSArray that I have to pass.
array([0] => array('latitude'=>'10.010490',
'longitude'=>'76.360779',
'altitude'=>'30.833334',
'timestamp'=>'11:17:23',
'speed'=>'0.00',
'distance'=>'0.00');
[1] => array('latitude'=>'10.010688',
'longitude'=>'76.361378',
'altitude'=>'28.546305',
'timestamp'=>'11:19:26',
'speed'=>'1.614',
'distance'=>'198.525711')
)`
and the required format is like this
[
{ "latitude":"10.010490",
"longitude":"76.360779",
"altitude":"30.833334",
"timestamp":"11:17:23",
"speed":"0.00",
"distance":"0.00"
},
{
"latitude":"10.010688",
"longitude":"76.361378",
"altitude":"28.546305",
"timestamp":"11:19:26",
"speed":"1.614",
"distance":"198.525711"
}
]
Any one have solution? Thanks in advance.
NSDictionary *firstJsonDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
#"10.010490", #"latitude",
#"76.360779", #"longitude",
#"30.833334", #"altitude",
#"11:17:23", #"timestamp",
#"0.00", #"speed",
#"0.00", #"distance",
nil];
NSDictionary *secondJsonDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
#"10.010490", #"latitude",
#"76.360779", #"longitude",
#"30.833334", #"altitude",
#"11:17:23", #"timestamp",
#"0.00", #"speed",
#"0.00", #"distance",
nil];
NSMutableArray * arr = [[NSMutableArray alloc] init];
[arr addObject:firstJsonDictionary];
[arr addObject:secondJsonDictionary];
NSData *jsonData2 = [NSJSONSerialization dataWithJSONObject:arr options:NSJSONWritingPrettyPrinted error:&error];
NSString *jsonString = [[NSString alloc] initWithData:jsonData2 encoding:NSUTF8StringEncoding];
NSLog(#"jsonData as string:\n%#", jsonString);
The simplest and best approach !!!
To convert NSArray or NSMutableArray into jsonString you can first convert it into NSData and then further convert that into a NSString. Use this code
NSData* data = [ NSJSONSerialization dataWithJSONObject:yourArray options:NSJSONWritingPrettyPrinted error:nil ];
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
It helped me and hope it helps you as well. All the best.
I would recommend the SBJson-Framework.
Converting an NSMutableArray is as simple as NSString *jsonString = [yourArray JSONRepresentation];
Edit: Jack Farnandish is right u have to transform it into a NSDictionary before you can convert it to Json. In my example the NSMutableArray has to contain the Dictionary. The Array is only needed to create the square brackets at the beginning and the end of the string.
You can use the build in JSON functions of iOS or use an external lib e.g. JSONKit to convert your data to JSON
First You must change you structure into NSDictionary class and NSArray containing NSDictionary objects, then try JSONKit in iOS 5 serialization works better than standard NSJSONSerialization.
#import <JSONKit/JSON.h>
NSArray *array = // Your array here.
NSString *json = [array JSONString];
NSLog(#"%#", json);
JSONKit performs significantly better than SBJson and others in my own and the author's benchmarks.
Check this tutorial, JSON in iOS 5.0 was clearly explained (serailization, deserailization).
Is the service you are calling a RESTful service?
If so, I'd strongly recommend using RestKit. It does object serialization/deserialization. It also handles all the networking underpinnings. Extremely valuable, and well maintained.

value stored during initialization is never read

I am trying parse the google api so that I can retrieve the address and its data.
I get two errors that are on the commented lines. Why am I getting these errors.
I allocated the dit so I should have to release it correct.
Here is my code to retrieve the data
NSURL *url=[NSURL URLWithString:str];
NSData *data=[[NSData alloc]initWithContentsOfURL:url];
NSString *str1=[[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]autorelease];
NSDictionary *dit=[[[NSDictionary alloc]init]autorelease];//value stored to dit during initialization is never read
dit=[str1 JSONValue];
NSArray *dit1=(NSArray *) [dit objectForKey:#"results"];
NSDictionary *dit3=[[dit1 objectAtIndex:0]objectForKey:#"geometry"];
NSDictionary *dit4=[dit3 objectForKey:#"bounds"];
NSDictionary *northeast=[dit4 objectForKey:#"northeast"];
NSDictionary *lt=[northeast objectForKey:#"lat"];
NSDictionary *southwest=[dit4 objectForKey:#"southwest"];
NSDictionary *lng=[southwest objectForKey:#"lng"];
Probably the issue is this:
NSDictionary *dit=[[[NSDictionary alloc]init]autorelease];
dit=[str1 JSONValue];
You create an empty dictionary, then never use it but instead overwrite the value with the one returned from JSONValue. This code should be:
NSDictionary *dit=[str1 JSONValue];

How To Parse JSON Format in Objective C

Hey every one i am programming an iphone app to get google search results into my app ,,, i have used the JSON Class to get the result ... when i parsed it in JSON Parser and store it in NSDictionary i got 3 keys :
responseData
responseDetails
responseStatus
the important one is the first one responseData which is has the search results ...
the problem that there is (i think) another key within responseData which is "results" which contains the urls and other stuffs which is the most important part for my app... how to access this one and put it into NSDictionary .....
this is the request :
http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=Paris%20Hilton
and to make things clear please consider to put that request into your browser and when you get the results copy it and put it in this website at the left side to see what the keys and other things:
http://json.parser.online.fr/
thnx
You could use JSON parser - SB Json to convert json string into ObjectiveC objects. Note that there are a number of JSON parsers available in ObjectiveC but I chose SB Json for it's ease of usage. But according to some benchmarks JSONKit is faster than SBJson.
Once you have your json string use this like so -
#import "JSON.h"
// Create SBJSON object to parse JSON
SBJSON *parser = [[SBJSON alloc] init];
// parse the JSON string into an object - assuming json_string is a NSString of JSON data
NSDictionary *object = [parser objectWithString:json_string error:nil];
NSLog(#"JSON data: %#", object);
Here's what you would do if you needed to parse public timeline from Twitter as JSON.The same logic could be applied to your Google Search results. You need to carefully inspect your json structure that's all...
// Create new SBJSON parser object
SBJSON *parser = [[SBJSON alloc] init];
// Prepare URL request to download statuses from Twitter
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://twitter.com/statuses/public_timeline.json"]];
// Perform request and get JSON back as a NSData object
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
// Get JSON as a NSString from NSData response
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
// parse the JSON response into an object
// Here we're using NSArray since we're parsing an array of JSON status objects
NSArray *statuses = [parser objectWithString:json_string error:nil];
// Each element in statuses is a single status
// represented as a NSDictionary
for (NSDictionary *status in statuses)
{
// You can retrieve individual values using objectForKey on the status NSDictionary
// This will print the tweet and username to the console
NSLog(#"%# - %#", [status objectForKey:#"text"], [[status objectForKey:#"user"] objectForKey:#"screen_name"]);
}
Il me semble que vous savez déjà comment analyser JSON en forme NSDictionary, alors voici quelques suggestions sur la façon de forer vers le bas pour vos résultats détaillés en cascade. En anglais pour tout le monde.
responseData itself is an NSDictionary and results is an object within it. Results happens to be an array for the case you gave.
After you convert the JSON to NSDictionary form, you will have recursively converted all of the objects inside.
You might try something like this to get at what you are looking for:
Lets assume the the fully converted JSON is in a NSDictionary called response
NSDictionary *responseDate = [response objectForKey:#"responseData"];
NSArray *resultsArray = [responseData objectForKey:#"results"];
Now you can use an iterator or a for-loop to go through each result.
One word of caution is that if there is only one result, you should first test to see if the class of the object is NSArray. Also, if there are no results, you should test for that too.
So you may want to code it this way to handle these cases:
NSDictionary *responseDate = [response objectForKey:#"responseData"];
If ([[responseData objectForKey:#"results"] isKindOfClass [NSArray class]]) {
NSArray *resultsArray = [responseData objectForKey:#"results"];
... do other things to get to each result in the array ...
}
else if ([[responseData objectForKey:#"results"] isKindOfClass [NSDictionary class]]) {
// it looks like each individual result in returned in a NSDictionary in your example
... do the things to handle the single result ...
}
else {
// handle no results returned
}
The first thing you should do, if you do not understand exactly what's going on, is to NSLog the description of the JSON parser output. This will be a "nest" of NSDictionary and NSArray, and when you see the description output you will understand that there is a one-to-one mapping of JSON "object" to NSDictionary and JSON "array" to NSArray. So you "understand" the parser output the same way you "understand" the JSON source.
In your case you'd likely extract the "responseData" object, cast it to an NSDictionary, extract "results" from that, cast it (guessing here) to an NSArray, then iterate through that array to extract your individual results.

Cast JSON object (NSCFDictionary) to string and parse it

I'm working with facebook connect and trying to handle the JSON object that i'm receiving.
I invoked the requstWithGraphPath method and need to get back a JSON object,
tried to parse it and getting an error:
SBJSON *parser = [[SBJSON new] autorelease];
NSData *data = [[NSData alloc] initWithData:result];
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; -> in this line - "[__NSCFDictionary length]: unrecognized selector sent to instance"
NSArray *events = [parser objectWithString:jsonString];
What's the problem?
Can I get the string in an other way or parse the object differently?
Thanks.
If you are working with the delegate callback
- (void)request:(FBRequest *)request didLoad:(id)result;
the parsing work has been done for you. Traverse the NSDictionary or NSArray to find the data you are looking for. If you are working with the delegate callback
- (void)request:(FBRequest *)request didLoadRawResponse:(NSData *)data;
you should initialize an NSString with the data, and use the category method that SBJSON adds to NSString for creating an id. That is assuming the data is data that constructs a string.
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
id result = [jsonString JSONValue];
Are you sure the error happens on that line, or does it happen on the line above?
If result is an NSDictionary (or CFDictionary, same thing), then it is already parsed and you do not need to do that yourself — and it could cause that error message too, on the line above.
The line:
data = [[NSData alloc] initWithData:result];
is almost certainly not what you want to do, as it is equivalent to
data = [result copy];
assuming that result is an NSData object (or NSMutableData), which I'm guessing it isn't.