title: When to use a UIAlertView vs. UIActionSheet
body: <p>Are there situations where a UIAlertView is better to use than a UIActionSheet? What are the typical scenarios where you would use one over the other?</p>
  
  <p>I'm programming a navigation bar button to open a UIWebView in an external application, and at first I started programming a UIAlertView, then I thought that an action sheet might be better for this situation. </p>
  
  <p>Are there any formal guidelines for which to use in different situations? Thanks.</p>