iPhone, iOS 8: How to presentViewController smaller than original view controller?

I have two view controllers, I want to present view controller(VC) of the first VC. Second VC have smaller size. I want to show second view controller over the first one. Like a popover. You can imagine it, if we add another view controller that slides from bottom to top but stops at navigation bar.

Here is my code:

@IBAction func showSecondVC(sender: AnyObject) {

    let secondViewController = storyboard?.instantiateViewControllerWithIdentifier("SecondViewController") as! SecondViewController

    secondViewController.view.frame = CGRect(origin: CGPoint(x: view.frame.origin.x, y: header.frame.height), size: CGSize(width: view.frame.width, height: view.frame.height - header.frame.height))

    secondViewController.definesPresentationContext = true
    secondViewController.providesPresentationContextTransitionStyle = true

    secondViewController.modalPresentationStyle = UIModalPresentationStyle.CurrentContext

    self.presentViewController(secondViewController, animated: true, completion:nil)


}

You can see that I set frame for secondViewController. I want that it will be with this frame, but if I add completion block and show it's frame after animation, it will be same as first View Controller have.

Edit

I also want to mention, that I try to make this in Portrait orientation.

Thanks in advice.