title: how to add button in UIAlertController In IOS 9
body: <p>how we use <code>UIAlertView</code> in iOS 9 and how to add button in <code>UIAlertController</code></p>
  
  <pre><code>UIAlertController * alert=[UIAlertController 
  
  alertControllerWithTitle:@"Title" message:@"Message"preferredStyle:UIAlertControllerStyleAlert];
  
  UIAlertAction* yesButton = [UIAlertAction
                          actionWithTitle:@"Yes, please"
                          style:UIAlertActionStyleDefault
                          handler:^(UIAlertAction * action)
                          {
                              **//What we write here????????**
  
  
                          }];
  UIAlertAction* noButton = [UIAlertAction
                              actionWithTitle:@"No, thanks"
                             style:UIAlertActionStyleDefault
                             handler:^(UIAlertAction * action)
                             {
                                 **//What we write here????????**
  
                             }];
  
  [alert addAction:yesButton];
  [alert addAction:noButton];
  
  [self presentViewController:alert animated:YES completion:nil];
  </code></pre>