AFNetworking with AFHTTPClient with AFJSONRequestO

Question

I've been trying to get a grip on AFHTTPClient in the specific instance of dispatching a request to a REST-based service that requires OAuth authentication. I have no problem with creating the OAuth authentication using GTMOAuth.

I can also successfully marshall parameters to dispatch the request and obtain a well-formed JSON response using a hand-cobbled NSMutableURLRequest and both AFJSONRequestOperation and an NSURLConnection. Those latter two mechanics were my sanity check that I was touching the service correctly.

I get a response using

[AFHTTPClient HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation, id responseObject)] 

but no matter what — it's interpreted as text/plain. The returned object's class is __NCFData.

No bueno.

This bit of code doesn't want to return a response that's a dictionary of any sort.

- (IBAction) testFlickr {
// marshall parameters
NSString *urlStr = @"http://api.flickr.com/";
NSURL *url = [NSURL URLWithString:urlStr];

AFHTTPClient *client = [[AFHTTPClient alloc]initWithBaseURL:url];
[client registerHTTPOperationClass:[AFJSONRequestOperation class]];
[client setParameterEncoding:AFJSONParameterEncoding];
NSDictionary *params = [[NSDictionary alloc]initWithObjectsAndKeys:@"json", @"format", @"66854529@N00", @"user_id", @"1", @"jsoncallback", nil];

NSString *path = [[NSString alloc]initWithFormat:@"services/rest/?method=flickr.people.getPhotos"];

NSMutableURLRequest *af_request = [client requestWithMethod:@"GET" path:path parameters:params];

// flickrAuth instance variable is an instance of GTMOAuthAuthentication
[self.flickrAuth authorizeRequest:af_request];

[client setAuthorizationHeaderWithToken:[self.flickrAuth accessToken]];
[client setDefaultHeader:@"Accept" value:@"application/json"];

[client requestWithMethod:@"GET" path:path parameters:params];

LOG_FLICKR_VERBOSE(0, @"Can Authorize? %@", ([self.flickrAuth canAuthorize] ? @"YES":@"NO"));
LOG_FLICKR_VERBOSE(0, @"%@", client);


// first way of trying..
AFHTTPRequestOperation *af_operation = [client HTTPRequestOperationWithRequest:af_request success:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSString *str = [[NSString alloc] initWithData:responseObject
                                          encoding:NSUTF8StringEncoding];
    LOG_FLICKR_VERBOSE(0, @"Weird af_operation semantics, but.. %@", str);
    LOG_FLICKR_VERBOSE(0, @"Weird af_operation semantics returns %@", [responseObject class]);

} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    //
    LOG_FLICKR_VERBOSE(0, @"Weird af_operation semantics, error.. %@", error);

}];

[af_operation start];
}

This request goes through okay. The response data itself is what I'd expect, but it is not any kind of dictionary class.

I'd rather keep to using methods of AFHTTPClient (as opposed to, for example, [AFJSONRequestOperation JSONRequestOperationWithRequest]) so I can use AFHTTPClient's Reachability methods and so forth.

Strangely (to me, at least) if I do the request like this:

NSMutableURLRequest *aj_request = [client requestWithMethod:@"GET" path:path parameters:params];
[self.flickrAuth authorizeRequest:aj_request];

AFJSONRequestOperation *aj_operation = 
[AFJSONRequestOperation JSONRequestOperationWithRequest:af_request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
    LOG_FLICKR_VERBOSE(0, @"AFJSONRequestOperation %@", JSON);
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
    LOG_FLICKR_VERBOSE(0, @"AFJSONREquestOperation Error %@", error);
}];

[aj_operation start];

It fails with a "401" because it was expecting application/json in the response header and instead thinks it's received text/plain

But, if I do the request like this:

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[[NSURL alloc]initWithString:@"http://api.flickr.com/services/rest/?method=flickr.people.getPhotos&format=json&user_id=66854529@N00&nojsoncallback=1"]];
[self.flickrAuth authorizeRequest:request];

AFJSONRequestOperation *operation =
[AFJSONRequestOperation JSONRequestOperationWithRequest:request
                                                success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
                                                    LOG_FLICKR_VERBOSE(0, @"Success Flickr  =========\n%@ %@", JSON, [JSON valueForKeyPath:@"photos.total"]);
                                                    /////handler(JSON, nil);
                                                } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
                                                    LOG_FLICKR(0, @"URL Was %@", url);
                                                    LOG_FLICKR(0, @"Failed Flickr  ==========\n%@ %@", error, JSON);
                                                    /////handler(nil, error);
                                                }];
[operation start];

It works fine, including nice JSON, dictionary-formed data.

In the first instance, I'm using AFHTTPClient to produce the NSMutableURLRequest. In the second instance, I'm creating the NSMutableURLRequest on my own. In both cases I'm using AFJSONRequestOperation to dispatch the request leaving the only culprit for the problem to (besides myself..) AFHTTPClient.

In the first example that I can get to work, it's not returning JSON-y data.

In the second example AFHTTPClient seems to create an NSMutableURLRequest that blatantly fails — but (AFAICT) the same URL succeeds when that URL is created "by hand" using [NSMutableURLRequest requestWithURL].

I wonder — what am I missing when using AFHTTPClient?

Help?

Answer 1

In your first code example, it looks like you're doing NSMutableURLRequest *af_request = [client requestWithMethod:@"GET" path:path parameters:params]; and then setting default headers afterwards. Default headers only get applied to requests created after they were specified. Maybe that's where things are going amiss.

Also, that 401 error may be complaining about its content type, but 401 is an error status code, meaning that you're unauthenticated.

Answer 2

I ended up removing all the header parameters to isolate the problem, but it made no difference. Examining the response quite closely gave me a clue. While Flickr does return "JSON" it is not Lint-free, it seems and requires a tweak to one of the parameters. I had been sending jsoncallback=1 but it should be nojsoncallback=1. Once I fixed that parameter AFJSONRequestOperation handles the response correctly and parses the JSON.

My final code looks like this (for others, n.b. the nojsoncallback=1 parameter)

- (IBAction)testFlickrAFJSON:(id)sender
{
// marshall parameters
NSString *urlStr = @"http://api.flickr.com/";
NSURL *url = [NSURL URLWithString:urlStr];
//NSDictionary *params = [[NSDictionary alloc]initWithObjectsAndKeys:@"json", @"format", @"66854529@N00", @"user_id", nil];
NSDictionary *params = [[NSDictionary alloc]initWithObjectsAndKeys:@"json", @"format", @"66854529@N00", @"user_id", @"1", @"nojsoncallback", nil];
NSString *path = [[NSString alloc]initWithFormat:@"services/rest/?method=flickr.people.getPhotos"];

AFHTTPClient *client = [[AFHTTPClient alloc]initWithBaseURL:url];

NSMutableURLRequest *af_request = [client requestWithMethod:@"GET" path:path parameters:params];

[self.flickrAuth authorizeRequest:af_request];

LOG_FLICKR_VERBOSE(0, @"Can Authorize? %@", ([self.flickrAuth canAuthorize] ? @"YES":@"NO"));
AFJSONRequestOperation *af_operation_2 = [AFJSONRequestOperation JSONRequestOperationWithRequest:af_request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        LOG_FLICKR_VERBOSE(0, @"AFJSONRequestOperation Alt %@", JSON);
        LOG_FLICKR_VERBOSE(0,@"AFJSONRequestOperation Alt response MIMEType %@",[response MIMEType]);

    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
        LOG_FLICKR_VERBOSE(0, @"AFJSONREquestOperation Alt Error %@", error);
        NSHTTPURLResponse *resp = [[error userInfo] valueForKey:AFNetworkingOperationFailingURLResponseErrorKey];
        LOG_FLICKR_VERBOSE(0,@"AFJSONRequestOperation Alt Error response MIMEType %@",[resp MIMEType]);

    }];

    [af_operation_2 start];

}