title: How to rerequest permission once denied by user
body: <p>Users can post messages on Facebook using my application. iOS presents the users with the permission dialogue the first time they try to post ("foo app would like to post privately on your behalf" - Don't Allow / OK). Now it seems that this decision is a persisting one. Once this dialogue is completed either way, the user will never be asked again. </p>
  
  <p>Now, as this might have happened out of mistake I don't think this is good enough for the user. Is there a way to initiate this permission dialogue from code somehow?</p>