title: show spinner and remove it in the same block
body: <p>In a method that can take up to several seconds i have:</p>
  
  <pre><code>UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc]initWithFrame:CGRectMake(135,140,50,50)];
  spinner.color = [UIColor blueColor];
  [spinner startAnimating];
  [_mapViewController.view addSubview:spinner];
  
  // lots of code
  
  [spinner removeFromSuperview];
  </code></pre>
  
  <p>The spinner doesn't show up. Probably since the screen doesn't get update at that time.
  How can i get around this problem?</p>