Re-authenticate using access token

Hi Greg, I am using it in this way. But after all that it shows me that it session is expired and do you want to relink it.

if (![[DBSession sharedSession] isLinked])
{
[[DBSession sharedSession] updateAccessToken:@"" accessTokenSecret:@"" forUserId:@""];
self.restClient = [[DBRestClient alloc] initWithSession:[DBSession sharedSession]];
self.restClient.delegate = self;
NSLog(@"Reauthenticating");
[self performSelector:@selector(fetchAllDropboxData) withObject:nil afterDelay:0.2];
// [[DBSession sharedSession] linkFromController:self];
{
YourClientsViewController *control = [self.storyboard instantiateViewControllerWithIdentifier:@"YourClientsViewController"];
[self.navigationController pushViewController:control animated:YES];
}
else
{
[[DBSession sharedSession] linkFromController:self];
UIAlertView *view = [[UIAlertView alloc]initWithTitle:@"Account Login!" message:@"Your dropbox account has been login" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[view show];

if (!loadData)
{
loadData = @"";
}

// [MBProgressHUD showHUDAddedTo:self.view animated:YES];
[self performSelector:@selector(fetchAllDropboxData) withObject:nil afterDelay:0.2];
}

Can you please help me to modify this code so that it will work.