NSURLConnection doen't return data where dataWithContentsOfURL does - iphone

Question

I have an application and I used to get my json data with dataWithContentsOfURL.
But because I need to get it an asynchrone fashion.
Now that I use NSURLConnection to handle this I don't receive any useful data all I get is statuscode 200 in the didReceiveResponse method but didReceiveData is never called.
And at connectionDidFinishDownloading destinationURL returns null.
I have no idea wat couses this problem and I would really appreciate some help.
the delegate
#import "NetWorkToGuiDelegate.h"
#implementation NetWorkToGuiDelegate
#synthesize data;
#synthesize caller;
- (id) init: (SEL) pointer :(NSObject *) c;
{
doWhenDone = pointer;
self.caller = c;
data = [[NSMutableData alloc]init];
return self;
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *responseText = [[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding];
NSLog(#"%#",responseText);
}
- (void)connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *)destinationURL
{
NSLog(#"post download finished");
data = [NSData dataWithContentsOfURL:destinationURL];
NSLog(#"data: %#",data);
NSLog(#"URLconnection %#", connection.currentRequest);
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
[caller performSelector:doWhenDone withObject:data];
#pragma clang diagnostic pop
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[self.data setLength:0];
NSHTTPURLResponse *resp= (NSHTTPURLResponsae *) response;
NSLog(#"got responce with status %d",[resp statusCode]);
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)d
{
NSLog(#"data recieved %#",d);
[self.data appendData:d];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
[[[UIAlertView alloc] initWithTitle:NSLocalizedString(#"Error", #"")
message:[error localizedDescription]
delegate:nil
cancelButtonTitle:NSLocalizedString(#"OK", #"")
otherButtonTitles:nil] show];
NSLog(#"failed");
}
// Handle basic authentication challenge if needed
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
NSString *username = #"username";
NSString *password = #"password";
NSURLCredential *credential = [NSURLCredential credentialWithUser:username
password:password
persistence:NSURLCredentialPersistenceForSession];
[[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
}
#end
the call
NetWorkToGuiDelegate *nwgd = [[NetWorkToGuiDelegate alloc] init:#selector(login:) :self];
NSString *stringURL = [NSString stringWithFormat:#"%#%#%#%#", dk.baseURL, #"menu?code=",dk.loginCode,#"&v=1"];
NSURL *url = [NSURL URLWithString:stringURL];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
NSURLConnection *urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:nwgd];
[urlConnection start];
I'll just add that the call happens on the main thread

Answer 1

Actually there is a lot of points to make the answer of this question and there are so many questions on SO itself
Go through this nice post
And a must Read doc from apple itself.(contains code samples and explanations)
Hope this will solve the problems for you.
EDIT
-(void)startAConnection
{
// Create the request.
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.apple.com/"]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
// create the connection with the request
// and start loading the data
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection) {
// Create the NSMutableData to hold the received data.
// receivedData is an instance variable declared elsewhere.
receivedData = [NSMutableData data];
} else {
// Inform the user that the connection failed.
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
// This method is called when the server has determined that it
// has enough information to create the NSURLResponse.
// It can be called multiple times, for example in the case of a
// redirect, so each time we reset the data.
// receivedData is an instance variable declared elsewhere.
[receivedData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
[receivedData appendData:data];
}
- (void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error
{
// inform the user
NSLog(#"Connection failed! Error - %# %#",
[error localizedDescription],
[[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"Succeeded! Received %d bytes of data",[receivedData length]);
}
Call startAConnection to start the process
NOTE: Don't forget <NSURLConnectionDelegate> in the .h