How to present popover properly in iOS 8

I'm trying to add a UIPopoverView to my Swift iOS 8 app, but I am unable to access the PopoverContentSize property, as the popover does not show in the correct shape. my code:

var popover: UIPopoverController? = nil 

    func addCategory() {

    var newCategory = storyboard.instantiateViewControllerWithIdentifier("NewCategory") as UIViewController
    var nav = UINavigationController(rootViewController: newCategory)
    popover = UIPopoverController(contentViewController: nav)
    popover!.setPopoverContentSize(CGSizeMake(550, 600), animated: true)
    popover!.delegate = self
    popover!.presentPopoverFromBarButtonItem(self.navigationItem.rightBarButtonItem, permittedArrowDirections: UIPopoverArrowDirection.Any, animated: true)
}

output:

When I am doing the same thing through UIPopoverPresentationController, I still don't get it done. this is my code:

func addCategory() {

    var popoverContent = self.storyboard.instantiateViewControllerWithIdentifier("NewCategory") as UIViewController
    var nav = UINavigationController(rootViewController: popoverContent)
    nav.modalPresentationStyle = UIModalPresentationStyle.Popover
    var popover = nav.popoverPresentationController as UIPopoverPresentationController
    popover.delegate = self
    popover.popoverContentSize = CGSizeMake(1000, 300)
    popover.sourceView = self.view
    popover.sourceRect = CGRectMake(100,100,0,0)

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

}

I get the exact same output.

How do I customize the size of my popover? Any help would be highly appreciated!

Okay, A housemate took a look at it and figured it out:

 func addCategory() {

    var popoverContent = self.storyboard?.instantiateViewControllerWithIdentifier("NewCategory") as UIViewController
    var nav = UINavigationController(rootViewController: popoverContent)
    nav.modalPresentationStyle = UIModalPresentationStyle.Popover
    var popover = nav.popoverPresentationController
    popoverContent.preferredContentSize = CGSizeMake(500,600)
    popover.delegate = self
    popover.sourceView = self.view
    popover.sourceRect = CGRectMake(100,100,0,0)

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

}

That's the way.

You don't talk to the popover itself anymore, you talk to the view controller inside of it to set the content size, by calling the property preferredContentSize