title: iOS Facebook SDK - Check Permissions
body: <p>I have a Facebook SSO working perfectly on my app, using last release of Facebook Objective-C SDK.
  I need to ask an extra permission inside the app if user do "something". I don't need to ask that permission if user gave it to me before, so, I guess, in Facebook SDK there should be a method</p>
  
  <pre><code>-(BOOL) checkPermission:(NSString*) permission;
  </code></pre>
  
  <p>so I can use it like this:</p>
  
  <pre><code>if( [facebook checkPermission:@"email"] ) {
  </code></pre>
  
  <p>Is there a way to do this? </p>