NSURLConnection doesn't receive data - iphone

Question

I have implemented an NSURLConnection that sends a request to a server and receives some data back which is stored in an NSMutableData object. These are the methods that I implemented as part of NSURLConnectionDelegate:
-(void)upLoadBook:(NSMutableDictionary *)theOptions{
NSMutableString *theURL = [[NSMutableString alloc] initWithString:#"theURL"];
[theURL appendFormat:#"&Title=%#&Author=%#&Price=%#", [theOptions objectForKey:#"bookTitle"],
[theOptions objectForKey:#"bookAuthor"],
[theOptions objectForKey:#"bookPrice"]];
[theURL appendFormat:#"&Edition=%#&Condition=%#&Owner=%#", [theOptions objectForKey:#"bookEdition"],
[theOptions objectForKey:#"bookCondition"],
_appDel.userID];
NSLog(#"%#\n", theURL);
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:theURL]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:10.0];
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];
}
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[receivedData appendData:data];
}
- (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)connectionDidFinishLoading:(NSURLConnection *)connection
{
// do something with the data
// receivedData is declared as a method instance elsewhere
//Receives a response after book has been uploaded (Preferably a Book ID...)
responseString = [[NSString alloc] initWithData:receivedData
encoding:NSUTF8StringEncoding];
NSLog(#"Response String: %#", responseString);
[_options setValue:responseString forKey:#"bookID"];
[self performSegueWithIdentifier:#"UploadSuccessSegue" sender:self];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Whoops." message:#" No internet
connection.\n Please make sure you have a connection to the internet."
delegate:self cancelButtonTitle:#"Ok"
otherButtonTitles: nil];
[alert show];
}
The function uploadBook seems to be called,however, I never get to didFinishLoading and didReceiveData never receives any data. What could be a possible problem. Any hints or clues would be much appreciated.

Answer 1

You need to add your NSURLConnection to the current run loop or a separate one (such as one you set up in a separate thread). The delegate methods do need to get CPU time, after all.
Looking at this related question's accepted answer, it can also be done via Grand Central Dispatch:
dispatch_async(dispatch_get_main_queue(), ^{
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
[conn start];
});

Answer 2

One thing for sure is that you should %-escape your list of parameter before trying to send the request.
You can use stringByAddingPercentEscapesUsingEncoding for that purpose:
NSMutableString *theURL = [[NSMutableString alloc] initWithString:#""];
[theURL appendFormat:#"&Title=%#&Author=%#&Price=%#", [theOptions objectForKey:#"bookTitle"],
[theOptions objectForKey:#"bookAuthor"],
[theOptions objectForKey:#"bookPrice"]];
[theURL appendFormat:#"&Edition=%#&Condition=%#&Owner=%#", [theOptions objectForKey:#"bookEdition"],
[theOptions objectForKey:#"bookCondition"],
_appDel.userID];
theURL = [NSStringWithFormat:#"YOUR_URL_HERE?",[theURL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
Please, note that I refactored your code with the minimum number of changes to get the result. You can find better refactorizations for sure.

Answer 3

Here is a sample that works from one of my projects:
NSMutableURLRequest *urlRequest = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:#"http://www.brayden.me/analytics/device.php"]];
[urlRequest setHTTPMethod:#"POST"];
NSMutableString *postParams = [NSMutableString string];
[postParams appendFormat:#"session=%#&", analyticsSession];
[postParams appendFormat:#"device=%#&", device];
[postParams appendFormat:#"system=%#&", csystem];
[postParams appendFormat:#"version=%#&", version];
[postParams appendFormat:#"launch=%f&", totalLaunchTime];
if([Analytics_Location location].latitude && [Analytics_Location location].longitude) {
[postParams appendFormat:#"latitude=%#&", [Analytics_Location location].latitude];
[postParams appendFormat:#"longitude=%#&", [Analytics_Location location].longitude];
}
[urlRequest setHTTPBody:[postParams dataUsingEncoding:NSUTF8StringEncoding]];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self startImmediately:YES];
[connection start];
Make sure your header method also uses . The code of mine should at least show you how to properly format the request, as I can verify this does receive data from a PHP call of mine.