creatig a asynchronus request

Question

I am trying to implement an asynchornus request . I did my research and this is the best I got but the code is full of errors that I do not find the solution for

   NSURL *url2 = [NSURL URLWithString:@"www.google.com"];

    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url2];
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];

    [NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
    {
        if ([data length] > 0 && error == nil)
            [delegate receivedData:data];//i get the error here use of undeclared identifier 'delegate' ,when I put self insead I receive the error : no visible @interface for "my class name"  declares the selector "received data"
        else if ([data length] == 0 && error == nil)
            [delegate emptyReply];//same error here 
        else if (error != nil && error.code == ERROR_CODE_TIMEOUT) //the error here is "use of undelcared identifier ERROR_CODE_TIMEOUT
            [delegate timedOut];//error here is save as the first one
        else if (error != nil)
            [delegate downloadError:error];//error here is save as the first one
    }];

I have added NSURLConnectionDelegate in my .h file

can somebody tell me what is the error ?

Thanks

Answer 1

I don't have much experience with this method, but this example works. I sent this to my server to test getting product info for an in-app purchase. You could put more else-ifs into it to, like you posted, to test for different possible outcomes, but this should get you started. I'm not sure why that stub you posted has references to a delegate -- the point (or one of the points) of block methods is to be able to do these kinds of things without a delegate.

- (void)makeConnection {
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:kServerPath]
                                          cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                      timeoutInterval:5];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:theRequest queue:queue completionHandler:^(NSURLResponse* theResponse, NSData* theData, NSError* error) {
    NSLog(@"%@,  %@  %@",theResponse.suggestedFilename,theResponse.MIMEType,theResponse.textEncodingName);
    if (theData != nil && error == nil) {
        NSArray *productArray = [NSJSONSerialization JSONObjectWithData:theData options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"%@",productArray);
    }else{
        NSLog(@"%@",error.localizedDescription);
    }
}];

}

Answer 2

I find it is easier to just do – initWithRequest:delegate: and implement the delegate methods as necessary. You'll want

- (void)connection:(NSURLConnection *)theConnection didReceiveResponse:(NSURLResponse *)response

and

- (void)connection:(NSURLConnection *)theConnection didReceiveData:(NSData *)data

at least. See http://developer.apple.com/library/ios/#samplecode/SimpleFTPSample/Listings/URLGetController_m.html for some code. Note that did receive data is called for incremental blocks. You probably want to keep track the total data in a property and append data as it arrives. Other than that, you can throw in error handling and authentication, but that should get you started.