OAuthCode invalid signature

[Evgeniy Pochitaev]

I'm trying integrate my app with freelancer.com api on iOS. I've used
OAuthCore library to work OAuth, here is my code:

#define CONSUMER_KEY @"xxx"
#define CONSUMER_SECRET @"xxx"

#define FREELANCER_API_URL(request1, request2) [NSString
stringWithUTF8String:"http://api.sandbox.freelancer.com/" #request1
"/" #request2 ".json"]
NSURL *url = [[NSURL alloc]
initWithString:FREELANCER_API_URL(RequestRequestToken,
requestRequestToken)];
NSData *body = [NSData data];
NSString *method = @"GET";
NSString *header = OAuthorizationHeader(url, method, body,
CONSUMER_KEY, CONSUMER_SECRET, @"", @"");
NSMutableURLRequest *request = [NSMutableURLRequest
requestWithURL:url];
[request setHTTPMethod:method];
[request setValue:header forHTTPHeaderField:@"Authorization"];
[request setHTTPBody:body];
NSURLResponse *response = nil;
NSError *error = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response error:&error];
NSLog(@"%@", [NSString stringWithUTF8String:(const char *)[data
bytes]]);

Output is:

{"errors":{"error":{"code":"5002","msg":"General Token Authentication
Error",
"longmsg":"Authentication Failed. Reason: invalid signature"}}}
Before OAuthCode I've used OAuthConsumer. OAuthConsumer retrieve same
error.

Any advices?

Thanks.