集合视图作为自定义键盘不起作用

我正在构建您具有自定义键盘的应用程序。

在它的类中，我创建了集合视图，这是代码：

class KeyboardViewController: UIInputViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, UICollectionViewDelegate {

let stickerImages = [
    UIImage(named: "Image-1"),
    UIImage(named: "Image-2"),
    UIImage(named: "Image-3"),
    UIImage(named: "Image-4"),
    UIImage(named: "Image-5")
]

@IBOutlet var nextKeyboardButton: UIButton!
@IBOutlet var collectionView: UICollectionView!

override func updateViewConstraints() {
    super.updateViewConstraints()
}

override func viewDidLoad() {
    super.viewDidLoad()

    let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
    layout.scrollDirection = UICollectionView.ScrollDirection.vertical
    layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
    layout.itemSize = CGSize(width: 50, height: 50)

    collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
    collectionView.dataSource = self
    collectionView.delegate = self
    collectionView.register(StickersCell.self, forCellWithReuseIdentifier: StickersCell.reuseIdentifier)
    collectionView.backgroundColor = UIColor.white
    collectionView.showsHorizontalScrollIndicator = false
    collectionView.backgroundColor = UIColor.red

    collectionView.translatesAutoresizingMaskIntoConstraints = false

    self.view.addSubview(collectionView)

    self.nextKeyboardButton = UIButton(type: .system)

    self.nextKeyboardButton.setTitle(NSLocalizedString("Next Keyboard", comment: "Title for 'Next Keyboard' button"), for: [])
    self.nextKeyboardButton.sizeToFit()
    self.nextKeyboardButton.translatesAutoresizingMaskIntoConstraints = false
    self.nextKeyboardButton.backgroundColor = UIColor.white

    self.nextKeyboardButton.addTarget(self, action: #selector(handleInputModeList(from:with:)), for: .allTouchEvents)

    self.view.addSubview(self.nextKeyboardButton)

    self.nextKeyboardButton.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
    self.nextKeyboardButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true

    self.collectionView.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
    self.collectionView.rightAnchor.constraint(equalTo: self.view.rightAnchor).isActive = true
    self.collectionView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
    self.collectionView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
}

override func textWillChange(_ textInput: UITextInput?) {
    // The app is about to change the document's contents. Perform any preparation here.
}

override func textDidChange(_ textInput: UITextInput?) {
    // The app has just changed the document's contents, the document context has been updated.

    var textColor: UIColor
    let proxy = self.textDocumentProxy
    if proxy.keyboardAppearance == UIKeyboardAppearance.dark {
        textColor = UIColor.white
    } else {
        textColor = UIColor.black
    }
    self.nextKeyboardButton.setTitleColor(textColor, for: [])
}

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

    return stickerImages.count
}

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

    cell.setImage(stickerImages[indexPath.item]!)

    return cell
}}

这是我的“收藏夹视图”单元格类：

class StickersCell: UICollectionViewCell {

static let reuseIdentifier: String = "StickersCell"

lazy var imageView: UIImageView = {
    let imageView = UIImageView(frame: .zero)
    imageView.contentMode = .scaleAspectFit
    imageView.translatesAutoresizingMaskIntoConstraints = false
    return imageView
}()

override init(frame: CGRect) {
    super.init(frame: frame)
    contentView.clipsToBounds = true
    contentView.addSubview(imageView)

    imageView.leftAnchor.constraint(equalTo: contentView.leftAnchor).isActive = true
    imageView.rightAnchor.constraint(equalTo: contentView.rightAnchor).isActive = true
    imageView.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
    imageView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor).isActive = true
}

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

func setImage(_ image: UIImage) {
    imageView.image = image
}}

在将集合视图添加到任何视图UIView或时UIViewController，此代码可以正常工作，但是在尝试将其添加到键盘时会引发以下错误：

据我了解，我将约束放置在错误的位置，但是我不明白到底是什么错误，尤其是当它在简单视图或视图控制器中正常工作时。

我用谷歌搜索了分配，找不到任何解决方案。同样，这个问题也没有帮助：

1. 第一个问题
2. 第二个问题
3. 第三个问题

我也尝试过将创建集合视图的代码移动到viewDidAppear和viewWillAppear方法中，但同样没有运气。

另一个奇怪的事情是：如果我UIView在键盘上添加具有相同约束的简单键-一切正常。问题似乎专门针对集合视图。

那么，我错过了什么？感谢您的帮助，因为我已经为这个问题奋斗了一个多星期...

更新：

在阅读了Apple开发人员论坛之后，我想到了UITableView一个主意：我创建了与UICollectionView以前相同的东西，但奇怪的是它起作用了。因此，下一个问题是：您是否完全可以UICollectionView用作自定义键盘？