Twitter Reverse Auth API Request

reverseAuth.m

- (void)reserveAuth
{
    
    NSString * http_method = @"POST";
    NSString * request_url = @"https://api.twitter.com/oauth/request_token";
    NSString * oauth_consumer_key = @"bcn3PUKI0PZoxfPTqEDkMru9A";
    NSString * oauth_consumer_secret = @"YiVeSteQBplk8xzAtuoulA7i2vLkVF5kIwc5x1A6ZaxmugdmXg";
    NSString * oauth_nonce = [[NSUUID UUID] UUIDString];
    NSString * oauth_signature = @"";
    NSString * oauth_signature_method = @"HMAC-SHA1";
    NSString * oauth_timestamp = [NSString stringWithFormat:@"%.0f", [[NSDate date] timeIntervalSince1970]];
    NSString * oauth_version = @"1.0";
    NSString * x_auth_mode = @"reverse_auth";
    
    NSMutableString *parameter_string = [NSMutableString string];
    
    [parameter_string appendFormat:@"oauth_consumer_key=%@&", oauth_consumer_key];
    [parameter_string appendFormat:@"oauth_nonce=%@&", oauth_nonce];
    [parameter_string appendFormat:@"oauth_signature_method=%@&", oauth_signature_method];
    [parameter_string appendFormat:@"oauth_timestamp=%@&", oauth_timestamp];
    [parameter_string appendFormat:@"oauth_token=&"];
    [parameter_string appendFormat:@"oauth_version=%@&", oauth_version];
    [parameter_string appendFormat:@"x_auth_mode=%@", x_auth_mode];
    
    NSMutableString * signature_base_string = [NSMutableString string];
    
    [signature_base_string appendFormat:@"%@", http_method];
    [signature_base_string appendString:@"&"];
    [signature_base_string appendFormat:@"%@", [self percentEncodeString:request_url]];
    [signature_base_string appendString:@"&"];
    [signature_base_string appendFormat:@"%@", [self percentEncodeString:parameter_string]];
    
    NSString * signing_key = [NSString stringWithFormat:@"%@&", [self percentEncodeString:oauth_consumer_secret]];
    
    const char *cKey  = [signing_key cStringUsingEncoding:NSASCIIStringEncoding];
    const char *cData = [signature_base_string cStringUsingEncoding:NSASCIIStringEncoding];
    
    unsigned char cHMAC[CC_SHA1_DIGEST_LENGTH];
    
    CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
    
    oauth_signature = [[[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)] base64EncodedStringWithOptions:0];
    
    NSMutableString *header = [NSMutableString stringWithString:@"OAuth "];
    
    [header appendFormat:@"oauth_consumer_key=\"%@\", ", oauth_consumer_key];
    [header appendFormat:@"oauth_nonce=\"%@\", ", oauth_nonce];
    [header appendFormat:@"oauth_signature=\"%@\", ", [self percentEncodeString:oauth_signature]];
    [header appendFormat:@"oauth_signature_method=\"%@\", ", oauth_signature_method];
    [header appendFormat:@"oauth_timestamp=\"%@\", ", oauth_timestamp];
    [header appendFormat:@"oauth_token=\"%@\", ", @""];
    [header appendFormat:@"oauth_version=\"%@\"", oauth_version];
    
    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    
    [manager setRequestSerializer:[[AFHTTPRequestSerializer alloc] init]];
    [manager setResponseSerializer:[[AFHTTPResponseSerializer alloc] init]];
    
    [[manager requestSerializer] setValue:header forHTTPHeaderField:@"Authorization"];
    [[manager responseSerializer] setAcceptableContentTypes:[NSSet setWithObject:@"text/html"]];
    
    [manager POST:request_url parameters:@{@"x_auth_mode": @"reverse_auth"} success:^(NSURLSessionDataTask *task, id responseObject)
    {
        NSString *string_value = [[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding];

        NSDictionary *step2Params = [[NSMutableDictionary alloc] init];
        [step2Params setValue:oauth_consumer_key forKey:@"x_reverse_auth_target"];
        [step2Params setValue:string_value forKey:@"x_reverse_auth_parameters"];
        
        NSURL *url2 = [NSURL URLWithString:@"https://api.twitter.com/oauth/access_token"];
        
        SLRequest *stepTwoRequest = [SLRequest requestForServiceType:SLServiceTypeTwitter
                                                       requestMethod:SLRequestMethodPOST
                                                                 URL:url2
                                                          parameters:step2Params];

        ACAccountStore *accountStore = [[AccountManager sharedManager] accountStore];
        ACAccount *twitterAccount = [[accountStore accounts] firstObject];

        [stepTwoRequest setAccount:twitterAccount];
        
        [stepTwoRequest performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
            NSString *responseStr = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
            
            [[AFHTTPSessionManager manager] POST:@"http://localhost:3000/user/connect/twitter"
                                      parameters:@{@"device": [[[UIDevice currentDevice] identifierForVendor] UUIDString],
                                                   @"account": @"twitter",
                                                   @"info": responseStr}
                                         success:^(NSURLSessionDataTask *task, id responseObject) {
                                             NSLog(@"%@", responseObject);
                                         } failure:^(NSURLSessionDataTask *task, NSError *error) {
                                             NSLog(@"%@", error);
                                         }];
        }];
        
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
        NSLog(@"%@", error);
    }];
}

- (NSString *)percentEncodeString:(NSString *)string
{
    CFStringRef charactersToLeaveUnescaped = CFSTR(" ");
    CFStringRef legalURLCharactersToBeEscaped = CFSTR("!$&'()+,/:;=?@~");
    
    NSString *result = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(
                                                                                 kCFAllocatorDefault,
                                                                                 (__bridge CFStringRef)string,
                                                                                 charactersToLeaveUnescaped,
                                                                                 legalURLCharactersToBeEscaped,
                                                                                 kCFStringEncodingUTF8));
    return [result stringByReplacingOccurrencesOfString:@" " withString:@"+"];
}

I don't know how to make request token.
Please help me.