Present modal view controller in half size parent controller

I am trying to present modal view controller on other viewcontroller sized to half parent view controller. But it always present in full screen view.

I have created freeform sized View controller in my storyboard with fixed frame size. 320 X 250.

var storyboard = UIStoryboard(name: "Main", bundle: nil)
var pvc = storyboard.instantiateViewControllerWithIdentifier("CustomTableViewController") as ProductsTableViewController
self.presentViewController(pvc, animated: true, completion: nil)

I have tried to set frame.superview and it doesn't help.

Please advice.

You can use a UIPresentationController to achieve this.

For this you let the presenting ViewController implement the UIViewControllerTransitioningDelegate and return your PresentationController for the half sized presentation:

func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
    return HalfSizePresentationController(presentedViewController: presented, presenting: presentingViewController)
}

When presenting you set the presentation style to .Custom and set your transitioning delegate:

pvc.modalPresentationStyle = .custom
pvc.transitioningDelegate = self

The presentation controller only returns the frame for your presented view controller:

class HalfSizePresentationController: UIPresentationController {
    override var frameOfPresentedViewInContainerView: CGRect {
        guard let bounds = containerView?.bounds else { return .zero }
        return CGRect(x: 0, y: bounds.height / 2, width: bounds.width, height: bounds.height / 2)
    }
}

Here is the working code in its entirety:

class ViewController: UIViewController, UIViewControllerTransitioningDelegate {

    @IBAction func tap(sender: AnyObject) {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let pvc = storyboard.instantiateViewController(withIdentifier: "CustomTableViewController") as! UITableViewController

        pvc.modalPresentationStyle = .custom
        pvc.transitioningDelegate = self
        pvc.view.backgroundColor = .red

        present(pvc, animated: true)
    }
    
    func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
        return HalfSizePresentationController(presentedViewController: presented, presenting: presentingViewController)
    }
}

class HalfSizePresentationController: UIPresentationController {
    override var frameOfPresentedViewInContainerView: CGRect {
        guard let bounds = containerView?.bounds else { return .zero }
        return CGRect(x: 0, y: bounds.height / 2, width: bounds.width, height: bounds.height / 2)
    }
}