iOS, RESTKit and oAuth - simple sample not working - ios

Question

I am writing a simple application on iOS and I am trying to consume a RESTFull webservice
To have some tips and get some knowledge I first start with twitter without using ios integrated libs, but I always get stocked on Auth.
Any working sample or link will be appreciated, as reminder twitter is not my final goal
For instance this is one of my code, based on RestKit and AFOAuth1Client :
NSURL *url = [NSURL URLWithString:#"https://api.twitter.com"];
AFOAuth1Client * twitterClient = [[AFOAuth1Client alloc] initWithBaseURL:url key:kCLIENTID secret:kCLIENTSECRET];
[twitterClient authorizeUsingOAuthWithRequestTokenPath:#"oauth/request_token"
userAuthorizationPath:#"oauth/authorize"
callbackURL:[NSURL URLWithString:#"af-twitter://success"]
accessTokenPath:#"oauth/access_token"
accessMethod:#"POST"
scope:#""
success:^(AFOAuth1Token *token, id responseObject) {
}
failure:^(NSError *error) {
}];
as you can see it does not work :
2013-06-17 16:59:01.389 restKitTest[14490:c07] I restkit:RKLog.m:34 RestKit logging initialized...
2013-06-17 16:59:02.653 restKitTest[14490:c07] I restkit.network:RKObjectRequestOperation.m:174 POST 'http://api.twitter.com/oauth/request_token'
2013-06-17 16:59:03.051 restKitTest[14490:c07] E restkit.network:RKObjectRequestOperation.m:203 POST 'http://api.twitter.com/oauth/request_token' (401 Unauthorized) [0.3980 s]: Error Domain=AFNetworkingErrorDomain Code=-1011 "Expected status code in (200-299), got 401" UserInfo=0x9c96640 {NSLocalizedRecoverySuggestion=Failed to validate oauth signature and token, AFNetworkingOperationFailingURLRequestErrorKey=<NSMutableURLRequest: 0x9877e20> { URL: http://api.twitter.com/oauth/request_token }, NSErrorFailingURLKey=http://api.twitter.com/oauth/request_token, NSLocalizedDescription=Expected status code in (200-299), got 401, AFNetworkingOperationFailingURLResponseErrorKey=<NSHTTPURLResponse: 0x9aac910> { URL: http://api.twitter.com/oauth/request_token } { status code: 401, headers {
"Cache-Control" = "no-cache, no-store, must-revalidate, pre-check=0, post-check=0";
"Content-Encoding" = gzip;
"Content-Length" = 62;
"Content-Type" = "text/html; charset=utf-8";
Date = "Mon, 17 Jun 2013 14:59:03 GMT";
Expires = "Tue, 31 Mar 1981 05:00:00 GMT";
"Last-Modified" = "Mon, 17 Jun 2013 14:59:03 GMT";
Pragma = "no-cache";
Server = tfe;
"Set-Cookie" = "_twitter_sess=BAh7CDoPY3JlYXRlZF9hdGwrCOJ3pVI%252FAToHaWQiJTIyYzUxN2UwNmUwYTI4%250AYzU1NmU0OTYxZDA5MDcwMmI3IgpmbGFzaElDOidBY3Rpb25Db250cm9sbGVy%250AOjpGbGFzaDo6Rmxhc2hIYXNoewAGOgpAdXNlZHsA--3291687666d367b6ccddc74513532bf56ea144d9; domain=.twitter.com; path=/; HttpOnly, guest_id=v1%3A137148114312677519; Domain=.twitter.com; Path=/; Expires=Wed, 17-Jun-2015 14:59:03 UTC";
Status = "401 Unauthorized";
Vary = "Accept-Encoding";
"x-frame-options" = SAMEORIGIN;
"x-mid" = af106773611449e1226d5dd5d531b64d91e4f3f8;
"x-runtime" = "0.01153";
"x-transaction" = 24e58d8eb3b7cdb5;
"x-ua-compatible" = "IE=10,chrome=1";
"x-xss-protection" = "1; mode=block";
} }}

Answer 1

"401 Unauthorized" indicates that your credentials are incorrect. So check your API keys.

Answer 2

try this:
[twitterClient authorizeUsingOAuthWithRequestTokenPath:#"/oauth/request_token"
userAuthorizationPath:#"/oauth/authorize"
callbackURL:[NSURL URLWithString:#"instantshare-twitter://success"]
accessTokenPath:#"/oauth/access_token"
accessMethod:#"POST"
scope:nil
success:^(AFOAuth1Token *accessToken, id responseObject) {
[twitterClient registerHTTPOperationClass:[AFJSONRequestOperation class]];
} failure:^(NSError *error) {
NSLog(#"Error: %#", error);
}];
Note the line scope:nil, for some reason it doesn't work with empty string.
Among other things, check your application settings in twitter. I'm not sure if this is the case, but I enabled Allow this application to be used to Sign in with Twitter and set Callback URL to some random valid url