How to send Asynchronous URL Request?

Question

I would like to know how do I get a return value 1 or 0 only.... back from an URL request asynchronously.

currently I do it in this way:

NSString *UTCString = [NSString stringWithFormat:@"http://web.blah.net/question/CheckQuestions?utc=%0.f",[lastUTCDate timeIntervalSince1970]]; NSLog(@"UTC String %@",UTCString); NSURL *updateDataURL = [NSURL URLWithString:UTCString]; NSString *checkValue = [NSString stringWithContentsOfURL:updateDataURL encoding:NSASCIIStringEncoding error:Nil]; NSLog(@"check Value %@",checkValue); 

this works, however it is blocking my main thread till I got a reply back from the URL, how do I set it so it will do it in a another thread instead of the main thread ?

EDIT: ANSWER I end upcalling my function with this, it works well :)

[self performSelectorInBackground:@selector(shouldCheckForUpdate) withObject:nil]; 

Answer 1

you can use NSURLConnection class

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]]; [[[NSURLConnection alloc] initWithRequest:request delegate:self] autorelease]; 

and handle its response and errors using its delegate methods.

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error - (void)connectionDidFinishLoading:(NSURLConnection *)connection  

You can find implementation of NSURLConnection

• Apple docs: Using NSURLConnection
• How To Use iOS NSURLConnection By Example

Edit: Although NSURLConnection is provided by apple is more recommended way of placing URL request. But I found AFNetworking library very time saving, easy to implement and robust yet simple as third party implementation. You should give it a try.

Answer 2

try this :

.h:

NSMutableData *responseData; 

.m:

- (void)load  {   NSURL *myURL = [NSURL URLWithString:@"http://www.example.com"];   NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:myURL cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60];    [[NSURLConnection alloc] initWithRequest:request delegate:self]; }  - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response  {   responseData = [[NSMutableData alloc] init]; }  - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data  {   [responseData appendData:data]; }  - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error  {   [responseData release];   [connection release];   [textView setString:@"Unable to fetch data"]; }  - (void)connectionDidFinishLoading:(NSURLConnection *)connection  {   NSLog(@"Succeeded! Received %d bytes of data",[responseData                                                    length]);   NSString *txt = [[[NSString alloc] initWithData:responseData encoding: NSASCIIStringEncoding] autorelease]; }