不知道为什么我的自定义 UICollectionViewCell 不起作用？

Question

我正在 Swift Playgrounds for iPad 中编写一个模拟消息应用程序。每次我运行 Playground 时，都会收到错误消息“运行此页面时出现问题。检查您的代码是否存在问题。如果您卡住了，请删除此页面上的所有内容，然后重试”。这是我到目前为止所拥有的。这很简单，我不确定我做错了什么。

import UIKit
import PlaygroundSupport

class ChatView : UICollectionViewController, UICollectionViewDelegateFlowLayout {
    override func viewDidLoad(){
        super.viewDidLoad()
        collectionView.register(ChatLogMessageCell.self, forCellWithReuseIdentifier: "cellId")
    }

        func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: IndexPath) -> UICollectionViewCell{
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! ChatLogMessageCell
            cell.messageTextView.text = "sample message text"
            return cell
        }

}



class ChatLogMessageCell : UICollectionViewCell {
    let messageTextView : UITextView = {
        let textView = UITextView()
        //textView.font = UIFont.systemFont(ofSize: 36)
        textView.text = "sample message"
        return textView
    }()

    func setupViews(){
        addSubview(messageTextView)
    }
}

PlaygroundPage.current.liveView = ChatView()

Answer 1

请尝试此解决方案。

import UIKit
import PlaygroundSupport

class ChatView : UICollectionViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.collectionView?.backgroundColor = .white
        self.collectionView?.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "cellId")
    }

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 2
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath)
        cell.backgroundColor = .green
        return cell
    }

}

PlaygroundPage.current.liveView = ChatView(collectionViewLayout: UICollectionViewFlowLayout())