JSON Parsing Error in ios - objective-c

Question

I want to fetch some data from some url and print result in nslog.
I am passing URl and want to fetch result in log only.
I have used this code :
-(void)GETJSONDATA
{
NSString*lu=#"tmp";
NSString *requestString = [[NSString alloc]init];
// [[NSUserDefaults standardUserDefaults] setValue:nil forKey:#"WRONGANSWER"];
NSLog(#"request string:%#",requestString);
NSData *requestData = [NSData dataWithBytes: [requestString UTF8String] length: [requestString length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:
[NSURL URLWithString: #"http://assessments.tlisc.org.au/webservices/questions/getbytaskpart.php?jsoncallback=?&token=1726204214321678|xTAieBBJoDaWmBsG1stxfq4zLO4&taskpartid=1"]];
NSString *postLength = [NSString stringWithFormat:#"%d", [requestData length]];
[request setHTTPMethod: #"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:requestData];
NSError *respError = nil;
NSData *returnData = [NSURLConnection sendSynchronousRequest: request returningResponse: nil error: &respError ];
if (respError)
{
// NSString *msg = [NSString stringWithFormat:#"Connection failed! Error - %# %#",
// [respError localizedDescription],
// [[respError userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]];
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Test" message:#"check your network connection" delegate:self cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alertView show];
}
else
{
NSString *responseString = [[NSString alloc] initWithData:returnData encoding: NSUTF8StringEncoding];
NSLog(#"Resp : %#",responseString);
NSDictionary *results = [responseString JSONValue];
NSLog(#"results=%#",results);
}
}
It is showing me this error :
-JSONValue failed. Error trace is: (
"Error Domain=org.brautaset.JSON.ErrorDomain Code=11 \"Unexpected end of string\" UserInfo=0x6a42be0 {NSLocalizedDescription=Unexpected end of string}"
Can anybody point me error?
In response string , it is showing null value.
I don't know the actual error.
it is working fine in browser but when I parse it it is showing this error....Is there anyway through which I can modify the url and get result ...i have checked my code with different url.and it is working proper..

Answer 1

I think I was using the same library as you're using here, and for some unexplained reason it just failed on a particular google api, sometimes getting results but usually failing. There appeared to be nothing wrong with the code.
In the end I went with the inbuilt NSJSONSerialization ( http://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSJSONSerialization_Class/Reference/Reference.html ) object and it hasn't failed since. I wasn't even aware there was JSON support built in (from iOS5 apparently).
I ran the two calls and processed them side by side, the external library continually failed. The internal methods worked fine.
Since I'm a beginner and the docs (above) don't really help me a lot, I used this tutorial http://www.raywenderlich.com/5492/working-with-json-in-ios-5 to get my head around it

Answer 2

As the error told you: the incoming JSON is not well-formed. Making a simple GET request to the URL you are using, I'm getting a JSON that is malformed, i.e. it is not valid JSON. I guess posting data to this URL returns the same format with actual data in it (not null).
Making use of a simple JSON Validator, I'm getting this
Parse error on line 5: ... "Description": "\n\tQuestion Numbe
-----------------------^ Expecting 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '['

Answer 3

Check your url in a browser. See the result. Your result's Structure should be like the same as JSON. if there is any other extra word in start of the json means. you should check your php code.

Answer 4

You have got HTML tags within your strings. Paragraph marks like
<p> and </p>
And these are not properly escaped. However, I do not know by hard wether the less than sign and greater than sign need to be escaped in JSON but apparently they are creating the issue.
Using google I find statements for both. However, some site suggests escaping < with \u003c and > with \u003e. that should do the trick.
I tried to validate the output from
http://assessments.tlisc.org.au/webservices/questions/getbytaskpart.php?jsoncallback=?&token=1726204214321678|xTAieBBJoDaWmBsG1stxfq4zLO4&taskpartid=1
It seems to be valid though if the <p> and </p> ist not interpreted by the bowser. (I was lookint to the "page source").
However, when escaped the string is still valid and encodes to the same result.
If this is not your issue, then please provide the output of your
NSLog(#"Resp : %#",responseString);