displaying CollectionViewController in Playground - xcode

Question

I am simply trying to display a CollectionView in playground to quickly try out ideas. Yet this has been a hour+ affair. I'm getting the error:
2017-03-17 17:28:37.862 uikitTest[88414:10270872] * Assertion failure in -[UICollectionView _dequeueReusableViewOfKind:withIdentifier:forIndexPath:viewCategory:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3600.6.21/UICollectionView.m:4971
2017-03-17 17:28:37.866 uikitTest[88414:10270872] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'could not dequeue a view of kind: UICollectionElementKindCell with identifier test1 - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'
*** First throw call stack:
I tried setting a view to the PlaygroundPage, and also creating a UIWindow. It isn't clear to me how to work with ViewControllers in Playground, and even whether this is the root problem and if its connected to the could not dequeue exception.
My Playground is as follows:
import UIKit
import XCPlayground
import PlaygroundSupport
class CVCCell: UICollectionViewCell {
let label = UILabel()
override init(frame: CGRect) {
super.init(frame: .zero)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func layoutSubviews() {
label.frame = bounds
}
}
class CVC: UICollectionViewController {
var datasource = ["1","2","3"]
override func viewDidLoad() {
view.backgroundColor = .red
print(collectionView)
collectionView?.register(CVCCell.self, forCellWithReuseIdentifier: "test1")
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return datasource.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "test1", for: indexPath) as! CVCCell
cell.label.text = datasource[indexPath.row]
return cell
}
}
let containerView = UIView(frame: CGRect(x: 0.0,
y: 0.0,
width: 375.0,
height: 667.0))
containerView.backgroundColor = .green
let fl = UICollectionViewFlowLayout()
let cvc = CVC(collectionViewLayout: fl)
let w = UIWindow(frame: CGRect(x: 0, y: 0, width: 320, height: 480))
w.rootViewController = cvc
print(cvc.view)
containerView.addSubview(cvc.view)
//PlaygroundPage.current.liveView = containerView