Using RestAPI calls with MGTwitterEngine+Oauth

I am using MGTwitterEngine+Oauth for twitter integration in iPhone. I need to post status and status with media on twitter.When searching I came to know that it can be possible with REST API. https://dev.twitter.com/docs/api

But I did not find any links which can help how to use this api after I get authenticated with twitter. So what I did I tried using Oauth but it requires manually entering the pin which is not accepted in my case. So what I did it. I fetch information from mgtwitter engine methods:-

- (void) OAuthTwitterController: (SA_OAuthTwitterController *) controller authenticatedWithUsername: (NSString *) username {





    NSLog(@"Inside authenticatedWithUsername");

    NSLog(@"%@",[[_engine tokenOFAuth] key]);

    NSLog(@"%@",[[_engine tokenOFAuth] pin]);

    NSLog(@"%@",[[_engine tokenOFAuth] secret]);

    [_engine getUserInformationFor:username]; 



}

tokenOFAuth is the instance of OAToken.



- (void)userInfoReceived:(NSArray *)userInfo forRequest:(NSString *)connectionIdentifier {



    NSLog(@"User Info Received: %@", userInfo);

    NSDictionary *userDict=[userInfo objectAtIndex:0];



    oAuth.user_id=[userDict objectForKey:@"id"];

    oAuth.screen_name=[userDict objectForKey:@"screen_name"];

    oAuth.oauth_token=[[_engine tokenOFAuth]key];

    oAuth.oauth_token_secret=[[_engine tokenOFAuth]secret];

    [oAuth synchronousAuthorizeTwitterTokenWithVerifier:[[_engine tokenOFAuth]pin]];    

    oAuth.oauth_token_authorized=YES;

    [oAuth saveOAuthTwitterContextToUserDefaults:oAuth];



[self sendTwitterTweetMethod];





}



-(void)sendTwitterTweetMethod

{

    [oAuth loadOAuthTwitterContextFromUserDefaults];

        NSString *postUrl = @"https://api.twitter.com/1/statuses/update.json";

        ASIFormDataRequest *request = [[ASIFormDataRequest alloc] initWithURL:[NSURL URLWithString:postUrl]];

        NSMutableDictionary *postInfo = [NSMutableDictionary dictionaryWithObject:@"I am testing my app" forKey:@"status"];

        for (NSString *key in [postInfo allKeys]) {

            [request setPostValue:[postInfo objectForKey:key] forKey:key];

        }

        [request addRequestHeader:@"Authorization" value:[oAuth oAuthHeaderForMethod:@"POST" andUrl:postUrl andParams:postInfo]];

        NSLog(@"[oAuth oAuthHeaderForMethod:@"" andUrl:postUrl andParams:postInfo]=%@",[oAuth oAuthHeaderForMethod:@"POST" andUrl:postUrl andParams:postInfo]);

        [request startSynchronous];

        NSLog(@"Status posted. HTTP result code: %d", request.responseStatusCode);

        [request release];





}



But it is giving response:-Status posted. HTTP result code: 401 which means unauthorized.

please suggest me to use this rest api with twitter+oauth and without manually entering pin also. I am stuck here.Please help. Any suggestions would be highly appreciated.