title: Present a UIAlertController from within a Popover in iOS8
body: <p>I set a UITableViewController to be displayed in a popover on iPad :
  <img src="https://i.stack.imgur.com/dM34T.png" alt="UITableViewController inside a popover"></p>
  
  <p>When I click on a row, I display an alert to warn the user of a potential destructive action.
  I used the new UIAlertController, and here is what happens:
  <img src="https://i.stack.imgur.com/NbYY8.png" alt="UIAlertViewController appears ..."></p>
  
  <p>The popover becomes very small (the size of the alertController view in fact). If I press Cancel, I can see the result :
  <img src="https://i.stack.imgur.com/JZ7Eb.png" alt="... making the popover shrink!"></p>
  
  <p>Here is my code:</p>
  
  <pre><code>override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
  
      var previouslySelectedCell: UITableViewCell?
      if checkedIndexPath != nil {
          previouslySelectedCell = tableView.cellForRowAtIndexPath(checkedIndexPath)
      }
      var selectedCell = tableView.cellForRowAtIndexPath(indexPath)
  
      let selectedCurrency = PortfolioCurrencyStore.sharedStore().allCurrencies[indexPath.row]
  
      if selectedCurrency.symbol != GlobalSettings.sharedStore().portfolioCurrency {
  
          // Warning : changing the portfolio currency will reset the portfolio
          var resetWarning = UIAlertController(title: NSLocalizedString("Currency Picker VC:AS title", comment: "Changing currency will reset portfolio"), message: nil, preferredStyle: .ActionSheet)
  
          // destructive button
          let resetAction = UIAlertAction(title: NSLocalizedString("Currency Picker VC:AS destructive", comment: "Destructive button title"), style: .Destructive, handler: { (action: UIAlertAction!) in
  
              // Remove checkmark from the previously marked cell
              previouslySelectedCell?.accessoryType = .None
  
              // Add checkmark to the selected cell
              selectedCell?.accessoryType = .Checkmark
              self.checkedIndexPath = indexPath
  
              // Animate deselection of cell
              self.tableView.deselectRowAtIndexPath(indexPath, animated:true)
  
              // Stock the portfolio currency as NSUserDefaults
              GlobalSettings.sharedStore().portfolioCurrency = selectedCurrency.symbol // link between portfolioCurrency as a String and currency.symbol as the property of a Currency instance.
  
              // Delete all items from the StockStore
              StockStore.sharedStore().removeAllStocks()
              println("StockStore : all entries were deleted")
  
  
              // Reload tableView
              self.tableView.reloadData()
  
              })
  
          // cancel button
          let cancelAction = UIAlertAction(title: NSLocalizedString("Currency Picker VC:AS cancel", comment: "Cancel button title"), style: .Cancel, handler:nil)
  
          resetWarning.addAction(resetAction)
          resetWarning.addAction(cancelAction)
  
          presentViewController(resetWarning, animated: true, completion: nil)
  
      } else {
          // Animate deselection of cell
          tableView.deselectRowAtIndexPath(indexPath, animated:true)
      }
  }
  </code></pre>
  
  <p>Did I miss something ?</p>
  
  <p>Thanks for your help</p>