QSTodoListViewController.m

- (void)viewDidAppear:(BOOL)animated
{
  MSClient *client = self.todoService.client;
  
  if (client.currentUser != nil) {
    return;
  }
  
  [client loginWithProvider:@"twitter" controller:self animated:YES completion:^(MSUser *user, NSError *error) {
    [self.todoService loadProducts:^{
      [self refresh];
    }];
  }];
}