Animate an UIView overlapping UINavigationBar ( Solution 1 - Using cloned view)

NavigationBarOverlappingDemo.swift

//
//  NavigationBarOverlappingDemo.swift
//
//  Created by Duc DoBa on 9/8/15.
//  Copyright (c) 2015 Duc Doba. All rights reserved.
//
//  This example is created to answer to the following StackOverflow question:
//  http://stackoverflow.com/questions/32446076/how-to-overlap-uinavigationbar-with-animation

import UIKit

class ViewController: UIViewController {
    // Simply put an UIImageView right under UINavigationBar to see the result
    @IBOutlet weak var imageView: UIImageView!
    
    // We will animate this object instead of the imageView
    // because moving the imageView back and forth between it's super view and window is quite troublesome
    lazy var clonedImageView: UIImageView = {
        var view = self.imageView.deepCopy() as! UIImageView
        let window = UIApplication.sharedApplication().keyWindow
        view.hidden = true
        window?.addSubview(view)
        
        return view
    }()
    
    override func viewDidAppear(animated: Bool) {
        var longPress = UILongPressGestureRecognizer(target: self, action: Selector("longPress:"))
        imageView.addGestureRecognizer(longPress)
        imageView.userInteractionEnabled = true
    }
    
    func longPress(gesture:UILongPressGestureRecognizer) {
        if gesture.state == UIGestureRecognizerState.Began {
            println("user pressed on image")
            
            self.showImageViewClone()
            let bounds = clonedImageView.bounds
            UIView.animateWithDuration(0.5, delay: 0.0, usingSpringWithDamping: 0.4, initialSpringVelocity: 10, options: UIViewAnimationOptions.CurveEaseInOut, animations: {
                self.clonedImageView.bounds = CGRect(x: bounds.origin.x, y: bounds.origin.y, width: bounds.size.width + 50, height: bounds.size.height + 50)
                }, completion: nil)
        }
        else if gesture.state == UIGestureRecognizerState.Changed {
            gesture.state == UIGestureRecognizerState.Began
        }
        else {
            println("user release on image")
            
            let bounds = clonedImageView.bounds
            UIView.animateWithDuration(0.2, animations: {
                self.clonedImageView.bounds = self.imageView.bounds
            }, completion: { _ in
                self.hideImageViewClone()
            })
        }
    }
    
    // This method is to ensure that the cloned imageView will appear exactly at the point you want
    func showImageViewClone() {
        let window = UIApplication.sharedApplication().keyWindow
        let origin = imageView.superview!.convertPoint(imageView.frame.origin, toView: window)
        
        var frame = clonedImageView.frame
        frame.origin = origin
        clonedImageView.frame = frame
        
        clonedImageView.hidden = false
        imageView.hidden = true
    }
    
    func hideImageViewClone() {
        self.imageView.hidden = false
        self.clonedImageView.hidden = true
    }
}

extension UIView {
    func deepCopy() -> UIView {
        
        let data = NSKeyedArchiver.archivedDataWithRootObject(self)
        let copy = NSKeyedUnarchiver.unarchiveObjectWithData(data)!  as! UIView
        
        return copy
    }
}