jsonParser objectWithString returns null value - ios

Question

declared in .h file
NSString *extractUsersGRC;
.m file
{
..
extractUsersGRC=[[NSString alloc]init];
extractUsersGRC = [[resultsGRC objectForKey:#"d"] retain];
NSDictionary *dict1 =[[NSDictionary alloc]init];
dict1=[[extractUsersGRC JSONValue]retain];
}
I am using json to get data from web service and web service is ok
replaying my request, but some times I am getting dict1 as nil.
jsonvalue returns me null.So where i am making mistake.
extractUsersGRC holding data but Jsonvalue returns null..? why ? I am
not getting Help me.
SBJSON *jsonGRC = [SBJSON new];
jsonGRC.humanReadable = YES;
responseData = [[NSMutableData data] retain];
NSString *service = #"/GET_Recent_Activity";
NSString *flagval=#"C";
double latval=[[[NSUserDefaults standardUserDefaults]valueForKey:#"LATITUDE"]doubleValue];
double longval=[[[NSUserDefaults standardUserDefaults]valueForKey:#"LONGITUDE"]doubleValue];
NSString *userid=[[NSUserDefaults standardUserDefaults]valueForKey:#"UserID"];
long u_id= [userid longLongValue];
NSLog(#"%ld",u_id);
NSString *requestString = [NSString stringWithFormat:#"{\"flag\":\"%#\",\"current_Lat\":\"%f\",\"current_Long\":\"%f\",\"userid\":\"%ld\"}",flagval,latval,longval,u_id];
NSLog(#"request string:%#",requestString);
NSData *requestData = [NSData dataWithBytes: [requestString UTF8String] length: [requestString length]];
NSString *fileLoc = [[NSBundle mainBundle] pathForResource:#"URLName" ofType:#"plist"];
fileContentsGRC = [[NSDictionary alloc] initWithContentsOfFile:fileLoc];
urlLocGRC = [fileContentsGRC objectForKey:#"URL"];
urlLocGRC = [urlLocGRC stringByAppendingString:service];
NSLog(#"URL : %#",urlLocGRC);
requestGRC = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString: urlLocGRC]];
NSString *postLength = [NSString stringWithFormat:#"%d", [requestData length]];
[requestGRC setHTTPMethod: #"POST"];
[requestGRC setValue:postLength forHTTPHeaderField:#"Content-Length"];
[requestGRC setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[requestGRC setHTTPBody: requestData];
NSError *respError = nil;
NSData *returnData = [NSURLConnection sendSynchronousRequest: requestGRC returningResponse: nil error: &respError ];

Answer 1

Declare #property (nonatomic, strong) NSMutableData *returnData; at .h file and
follow me
change your NSURLConnection declaration
NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (theConnection)
self.returnData = [[NSMutableData alloc] init];
else
NSLog(#"Connection Failed!");
and delegate method of NSURLConnection
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[self.returnData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[self.returnData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Network Error" message:#"Connection failed." delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles:nil];
[alert show];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *jsonString = [[NSString alloc] initWithData:self.returnData encoding:NSUTF8StringEncoding];
NSMutableDictionary *jsonDictionary = [jsonString JSONValue];
NSLog(#"%#", jsonDictionary);
}