gistfile1.swift

import UIKit

class demoViewController: UIViewController, UIPopoverPresentationControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        
    }
    
    
    @IBAction func button(sender: AnyObject) {
        let popover = UIViewController()
        popover.view.backgroundColor = UIColor.purpleColor()
        popover.modalPresentationStyle = .Popover
        
        popover.preferredContentSize = CGSizeMake(0, 0)
        
        UIView.animateWithDuration(1.0, animations: { () -> Void in
            popover.preferredContentSize = CGSizeMake(UIScreen.mainScreen().bounds.width, 100)

        })
        
        let popoverPresentationController = popover.popoverPresentationController
        popoverPresentationController?.permittedArrowDirections = UIPopoverArrowDirection.Up
        popoverPresentationController?.delegate = self
        popoverPresentationController?.sourceView = sender as! UIView
        popoverPresentationController?.sourceRect = sender.bounds
        
        self.presentViewController(popover, animated: true, completion: nil)
    }
    
    
    func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
        return UIModalPresentationStyle.None
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    

}