UICollectionView不填充自定义菜单项swift 3

Question

我对快速发展相对较新，我面临着一个让我永远需要解决的问题，我需要一些帮助。我创建了一个侧面菜单，由于某种原因，无法填充默认菜单项。我正在使用UICollectionView来填充菜单项。我以编程方式创建了collectionview和item。以下是我的代码：

import UIKit

class MenuCell: UICollectionViewCell {


    var nameLabel: UILabel!

    override init(frame: CGRect) {
        super.init(frame: frame)
        nameLabel = UILabel()
        nameLabel.text = "Scan NFC"
        contentView.addSubview(nameLabel)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

    }


    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

}



class MenuLauncher: NSObject, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
    let blackView = UIView()

    let collectionView: UICollectionView = {
      let layout = UICollectionViewLayout()
      let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
      cv.backgroundColor = UIColor.white
        return cv
    }()

    let cellId = "cellId"

    override init() {
        super.init()

        collectionView.register(MenuCell.self, forCellWithReuseIdentifier: cellId)
        collectionView.dataSource = self
        collectionView.delegate = self

        print("inside init")
    }

    @objc func showMenu(){
        //show menu items here
        if let window = UIApplication.shared.keyWindow{

            //add background color for when menu is shown
            blackView.backgroundColor = UIColor(white: 0 , alpha: 0.5)

            //set action handler for when user clicks anywher in the screen to dismiss the menu
            blackView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleDismiss)))
            window.addSubview(blackView)

            //add collection view
            window.addSubview(collectionView);


            //determine position of menu
            let height: CGFloat = 200
            let y = window.frame.height - height

            //in order to animate the menu you need to change the y value from y to window.frame.height
            collectionView.frame = CGRect(x: 0, y: window.frame.height, width: window.frame.width, height: 200)

            //add the subview to the whle window so that the background also covers the navigation bar
            blackView.frame = window.frame
            blackView.alpha = 0

            //accelerated animation
            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
                self.blackView.alpha = 1

                //set default height and width of menu
                self.collectionView.frame = CGRect(x: 0, y: y, width: self.collectionView.frame.width, height: self.collectionView.frame.height)

            }, completion: nil)

        }
    }

    @objc func handleDismiss(){
        UIView.animate(withDuration: 0.5, animations: {
            self.blackView.alpha = 0
            if let window = UIApplication.shared.keyWindow{
                self.collectionView.frame = CGRect(x: 0, y: window.frame.height, width: self.collectionView.frame.width, height: self.collectionView.frame.height)
            }
        })
    }

    //set default size of each element
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: collectionView.frame.width, height: 50)
    }



    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 3
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! MenuCell
        return cell
    }
}

  

的ViewController

override func viewDidLoad() {
    super.viewDidLoad()
    setupNavBarButtons()
    //get_data_from_url("http://www.kaleidosblog.com/tutorial/tutorial.json")
    // Do any additional setup after loading the view, typically from a nib.
}

func setupNavBarButtons(){
    let barButtonItem = UIBarButtonItem(image: UIImage(named: "Plus-Icon-40"),
                                        style: .plain,
                                        target: self,
                                        action: #selector(invokeMenu))
    navigationItem.rightBarButtonItems = [barButtonItem]

}

let menuLauncher = MenuLauncher()

@objc func invokeMenu() {
    menuLauncher.showMenu()
}