CODEWITHSUNDEEP
iosobjective-cjsonasynchronousafnetworking
blaa
blaa

Reputation: 438

IOS/AFNetworking: enqueue two JSON operations and then compare the returned NSArrays

For my app, I have to connect to two webservices that return JSON.

I first rolled my own networking code using GCD, but seeing how AFNetworking handles things, I decided to implement it. Most things went ok, but at some point I'm retrieving two arrays filled with objects. Those two arrays are then compared using a different method. Somehow the actual enqueueing is either delayed or not working, depending on the code I'm using.

When using: 

NSArray *operations = [NSArray arrayWithObjects:operation, operation1, nil];
        AFHTTPClient *client = [[AFHTTPClient alloc]init];

        [client enqueueBatchOfHTTPRequestOperations:operations progressBlock:nil completionBlock:^(NSArray *operations) {
            [self compareArrays:self];
        }

it just hangs.

When using:

 [operation start];
    [operation1 start];
    [operation waitUntilFinished];
    [operation1 waitUntilFinished];

    [self compareArrays:self];

at the end, it gets the arrays, but only compares after the UI has been formed.

EDIT: I checked Dave's answer, and it looks really streamlined. Would my app benefit from using the AFHTTPClient, or does this method (using AFJSONRequestOperation) offer the same features? I recall AFHTTPClient handling reachability on its own now (though you need to set it). I fiddled around a bit, and got this working:

NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    WebServiceStore *wss = [WebServiceStore sharedWebServiceStore];
    self.userData = wss.userData;
    serviceURL = [NSString stringWithFormat: @"WEBSERVICE URL"];
    NSString* zoekFruit = [NSString stringWithFormat:
                           @"%@?customer=%@&gebruiker=%@&password=%@&breedte=%@&hoogte=%@&diameter=%@",
                           serviceURL,
                           self.userData.Klant,
                           self.userData.Gebruiker,
                           self.userData.Wachtwoord,
                           breedte,
                           hoogte,
                           diameter];

    NSURL *url = [NSURL URLWithString:[zoekFruit stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding]];

        NSURLRequest *request = [NSURLRequest requestWithURL:url];

        AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
            id results = [JSON valueForKey:@"data"];

            [results enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

                //Initiate the BWBand

                BWBand *band = [[BWBand alloc]init];

                //Set the BWBand's properties with valueforKey (or so).                    

                [getBandenArray addObject:band];
            }];

            NSLog(@"getBandenArray: %@",getBandenArray);

        } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Error retrieving Banden" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
            [alert show];
        }];

       [queue addOperation:operation];

Upvotes: 2

Views: 2935

Answers (1)

Dave
Dave

Reputation: 7717

The AFNetworking class will allow you to create a bunch of operations, then hand them all off to be processed. You add some code to occur on success/failure for each individual request and/or when all requests have been processed.

Here's an outline of what you might do. I'll leave the details, actual comparison, and error handling to your imagination. :)

-(void)fetchAllTheData {
    NSMutableArray * operations = [NSMutableArray array];
    for (NSString * url in self.urlsToFetchArray) {
        [operations addObject:[self operationToFetchSomeJSON:url]];
    }
    AFHTTPClient *client = [AFHTTPClient clientWithBaseURL:[NSURL URLWithString:[PREFS objectForKey:@"categoryUrlBase"]]];
    [client enqueueBatchOfHTTPRequestOperations:operations
                                  progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
                                      NSLog(@"Finished %d of %d", numberOfFinishedOperations, totalNumberOfOperations);
                                  }
                                completionBlock:^(NSArray *operations) {
                                    DLog(@"All operations finished");
                                    [[NSNotificationCenter defaultCenter] postNotificationName:@"Compare Everything" object:nil];
                                }];
}

-(AFHTTPRequestOperation *)operationToFetchSomeJSON:(NSString*)whichOne {
    NSURL * jsonURL = [NSURL URLWithString:whichOne];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:jsonURL];
    [request setHTTPShouldHandleCookies:NO];
    [request addValue:@"application/json" forHTTPHeaderField:@"Accept"];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        NSLog(@"My data = %@", operation.responseString); // or responseData
        // Got the data; save it off.
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        DLog(@"Error downloading: %@  %@", whichOne, error);
    }];
    return operation;
}

Hope that helps.

Upvotes: 4

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