How to rotate UIAlertController in Swift

I have a working UIAlertController, but I want to rotate the alert.view by 90 degrees left.

How can I do it? My code is here below:

let alert = UIAlertController(title: "", message: "Message Sample", preferredStyle: .Alert)
alert.addAction(UIAlertAction(title: "Okay", style: .Default){(action)->() in })
presentViewController(alert, animated: true) {}

I tried to add:

 alert.view.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))

but it doesn't work.

Thank you !

With this code:

let alert = UIAlertController(title: "", message: "Message Sample", preferredStyle: .Alert)
alert.addAction(UIAlertAction(title: "Okay", style: .Default){(action)->() in })

self.presentViewController(alert, animated: true, completion: {() -> Void in
      alert.view.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))

})

Swift3

let alert = UIAlertController(title: "", message: "Message Sample", preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "Okay", style: .default){(action)->() in })

    self.present(alert, animated: true, completion: {() -> Void in
        alert.view.transform = CGAffineTransform(rotationAngle: CGFloat(Double.pi/2) )

    })

You can achieve this:

Updated answer

 self.presentViewController(alert, animated: true, completion: {() -> Void in
         // alert.view.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))

        UIView.animateWithDuration(1.0, delay: 0, options: .CurveLinear, animations: { () -> Void in
            alert.view.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))
        }) { (finished) -> Void in
          // do something if you need
        }

    })