How to add views to the bouncy/elastic areas of an NSScrollView.

views-for-bouncy-areas-of-NSScrollView.swift

//
//  SomeViewController.swift
//
//  Created by Boy van Amstel on 15/08/16.
//  Copyright © 2016 Danger Cove. All rights reserved.
//
//  To change the background color, simply modify .backgroundColors: [NSColor]

import Cocoa

/// A generic view controller that contains an element that uses a scroll view, like an NSCollectionView, NSTableView etc.
class SomeViewController: NSViewController {

  /// The collection view.
  @IBOutlet weak var collectionView: NSCollectionView!
  /// The clip view that contains the collection view.
  @IBOutlet weak var clipView: NSClipView!

  override func viewDidLoad() {
    super.viewDidLoad()
    // Do view setup here.
    
    // Adds a view to the top of the clip view
    let topView = NSView(frame: CGRectOffset(collectionView.frame, 0, -NSHeight(collectionView.frame)))
    topView.wantsLayer = true
    // Sets the view's background color to red
    topView.layer?.backgroundColor = NSColor.redColor().CGColor
    clipView.addSubview(topView)
    
    // Adds a view to the bottom of the clip view
    // Not working correctly... Should stick to the bottom, might need auto layout
//    let bottomView = NSView(frame: CGRectOffset(collectionView.frame, 0, NSHeight(collectionView.frame)))
//    bottomView.wantsLayer = true
//    // Sets the view's background color to red
//    bottomView.layer?.backgroundColor = NSColor.redColor().CGColor
//    clipView.addSubview(bottomView)

  }
}