Ios – Converting from ASIHTTPRequest to AFNetworking

afnetworkingasihttprequestiosiphonesdk

I am converting my app routines from ASIHTTP to AFNetworking due to the unfortunate discontinuation of work on that project … and what I found out later to be the much better and smaller codebase of AFNetworking.

I am finding several issues. My code for ASIHTTPRequest is built as a method. This method takes a few parameters and posts the parameters to a url … returning the resulting data. This data is always text, but in the interests of making a generic method, may sometimes be json, sometimes XML or sometimes HTML. Thus I built this method as a standalone generic URL downloader.

My issue is that when the routine is called I have to wait for a response. I know all the "synchronous is bad" arguments out there…and I don't do it a lot… but for some methods I want synchronous.

So, here is my question. My simplified ASIHTTP code is below, followed by the only way i could think of coding this in AFNetworking. The issue I have is that the AFNetworking sometimes does not for the response before returning from the method. The hint that @mattt gave of [operation waitUntilFinished] totally fails to hold the thread until the completion block is called… and my other method of [queue waitUntilAllOperationsAreFinished] does not necessarily always work either (and does NOT result in triggering the error portion of the [operation hasAcceptableStatusCode] clause). So, if anyone can help, WITHOUT The ever-present 'design it asynchronously', please do.

ASIHTTP version:

- (NSString *) queryChatSystem:(NSMutableDictionary *) theDict
{
    NSString *response = [NSString stringWithString:@""];
    NSString *theUrlString = [NSString stringWithFormat:@"%@%@",kDataDomain,kPathToChatScript];

    ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:theUrlString]];
    for (id key in theDict)
    {
        [request setPostValue:[theDict objectForKey:key] forKey:key];
    }

    [request setNumberOfTimesToRetryOnTimeout:3];
    [request setAllowCompressedResponse:YES];
    [request startSynchronous];

    NSError *error = [request error];
    if (! error)
    {
        response = [request responseString];
    }

    return response;
}

AFNetworking version

- (NSString *) af_queryChatSystem:(NSMutableDictionary *) theDict
{
    NSMutableDictionary *theParams = [NSMutableDictionary dictionaryWithCapacity:1];

    for (id key in theDict)
    {
        [theParams setObject:[theDict objectForKey:key] forKey:key];
    }


    AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:kDataDomain]];

    NSMutableURLRequest *theRequest = [httpClient requestWithMethod:@"POST" path:[NSString stringWithFormat:@"/%@",kPathToChatScript] parameters:theParams];


    __block NSString *responseString = [NSString stringWithString:@""];

    AFHTTPRequestOperation *operation = [[[AFHTTPRequestOperation alloc] initWithRequest:theRequest] autorelease];

    operation.completionBlock = ^ {
        if ([operation hasAcceptableStatusCode]) {
            responseString = [operation responseString];
            NSLog(@"hasAcceptableStatusCode: %@",responseString);
        }
        else
        {
            NSLog(@"[Error]: (%@ %@) %@", [operation.request HTTPMethod], [[operation.request URL] relativePath], operation.error);
        }
    };

    NSOperationQueue *queue = [[[NSOperationQueue alloc] init] autorelease];
    [queue addOperation:operation];
    [queue waitUntilAllOperationsAreFinished];
    [httpClient release];


    return responseString;

}

Thanks very much for any ideas.

Best Answer

- (void)af_queryChatSystem:(NSMutableDictionary *) theDict block:(void (^)(NSString *string))block {
...
}

Now within the completionBlock do:

block(operation.responseString);

block will act as the delegate for the operation. remove 

-waitUntilAllOperationsAreFinished

and 

return responseString

You call this like:

[YourInstance af_queryChatSystem:Dict block:^(NSString *string) {
    // use string here
}];

Hope it helps. You can refer to the iOS example AFNetworking has

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