ios - CollectionViewControllerCell 未显示 CollectionViewController 的问题

Question

我正在使用 Firebase 制作一个 iPhone 应用程序，但我在使用以下代码时遇到了一个小问题。

import UIKit
import Firebase

class ChatController: UICollectionViewController, UITextFieldDelegate, UICollectionViewDelegateFlowLayout {
    var game: Game? {
        didSet {
            navigationItem.title = game?.name
        }
    }

    lazy var inputTextField: UITextField = {
        let textField = UITextField()
        textField.placeholder = "Enter message..."
        textField.translatesAutoresizingMaskIntoConstraints = false
        return textField
    }()

    let cellId = "cellId"

    override func viewDidLoad() {
        super.viewDidLoad()

        collectionView?.alwaysBounceVertical = true
        collectionView?.backgroundColor = UIColor.white
        collectionView?.register(ChatMessageCell.self,  forCellWithReuseIdentifier: cellId)

        setupInputComponents()
    }

    var messages = [Message]()

    func observeMessages() {
        let ref = Database.database().reference().child("games").child((game?.id)!).child("messages")
        ref.observe(.childAdded, with: { (snapshot) in
            if let dictionary = snapshot.value as? [String: AnyObject] {
                let message = Message()
                message.setValuesForKeys(dictionary)
                self.messages.append(message)

                DispatchQueue.main.async {
                    self.collectionView?.reloadData()
                }
            }
        }, withCancel: nil)
    }

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

        return messages.count
    }

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

//        let message = messages[indexPath.item]
//        cell.textView.text = message.text
        cell.backgroundColor = UIColor.blue

        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: NSIndexPath) -> CGSize {
        return CGSize(width: view.frame.width, height: 80)
    }

    // Sets up the entire message sending
    // container for the send button and input
    // text field
        func setupInputComponents() {
        // Creates the container for send button
        // and input text field
        let containerView = UIView()
        containerView.backgroundColor = UIColor.white
        containerView.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(containerView)

        // anchor constraints and x,y,w,h
        // for positioning the container
        containerView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        containerView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        containerView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
        containerView.heightAnchor.constraint(equalToConstant: 50).isActive = true

        // Creates the send button
        let sendButton = UIButton(type: .system)
        sendButton.setTitle("Send", for: .normal)
        sendButton.translatesAutoresizingMaskIntoConstraints = false
        sendButton.addTarget(self, action: #selector(handleSend), for: .touchUpInside)
        containerView.addSubview(sendButton)

        // Positions the send button within the container
        sendButton.rightAnchor.constraint(equalTo: containerView.rightAnchor).isActive = true
        sendButton.centerYAnchor.constraint(equalTo: containerView.centerYAnchor).isActive = true
        sendButton.widthAnchor.constraint(equalToConstant: 80).isActive = true
        sendButton.heightAnchor.constraint(equalTo: containerView.heightAnchor).isActive = true

        // Creates the input text field
        containerView.addSubview(inputTextField)

        // Positions the send button within the container
        inputTextField.leftAnchor.constraint(equalTo: containerView.leftAnchor, constant: 8).isActive = true
        inputTextField.centerYAnchor.constraint(equalTo: containerView.centerYAnchor).isActive = true
        inputTextField.rightAnchor.constraint(equalTo: sendButton.leftAnchor).isActive = true
        inputTextField.heightAnchor.constraint(equalTo: containerView.heightAnchor).isActive = true

        // Create a seperator for this component
        let seperatorLineView = UIView()
        seperatorLineView.backgroundColor = UIColor(r: 220, g: 220, b: 220)
        seperatorLineView.translatesAutoresizingMaskIntoConstraints = false
        containerView.addSubview(seperatorLineView)

        // Positions the seperator
        seperatorLineView.leftAnchor.constraint(equalTo: containerView.leftAnchor, constant: 8).isActive = true
        seperatorLineView.widthAnchor.constraint(equalTo: containerView.widthAnchor).isActive = true
        seperatorLineView.topAnchor.constraint(equalTo: containerView.topAnchor).isActive = true
        seperatorLineView.heightAnchor.constraint(equalToConstant: 1).isActive = true
    }

    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }

    @objc func handleSend() {

        let ref = Database.database().reference().child("games").child("-L6lIJt_cw6saNNWMgu1").child("messages")
        ref.keepSynced(true)
        let childRef =  ref.childByAutoId()
        let values = ["text": inputTextField.text!]
        childRef.updateChildValues(values)
    }
}

我有一些注释掉的部分实际上是我想要在我的单元格中显示为文本的部分，但我什至无法让彩色框显示在 CollectionViewController 中。数据库检索代码工作得很好，我可以在 TableViewController 中显示它给我的内容。它只是不在我在这里创建的 CollectionViewController 中。

实际情况是应用程序成功构建和加载，但当我导航到此屏幕时，我正在创建的单元格没有显示。这些行具体如下:

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

    return messages.count
//        return 5
}

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

//        let message = messages[indexPath.item]
//        cell.textView.text = message.text
    cell.backgroundColor = UIColor.blue

    return cell
}


func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: NSIndexPath) -> CGSize {
    return CGSize(width: view.frame.width, height: 80)
}

Answer 1

您需要添加以下委托(delegate)和数据源。

在你的类中添加 UICollectionViewDataSource 和 UICollectionViewDelegate。

然后在您的 viewDidLoad 中添加 self.collectionView?.delegate = self 和 self.collectionView?.dataSource = self。

这告诉 View Controller 它的委托(delegate)和数据源方法在它自己的类中。这应该可以解决您的问题。抱歉，如果此答案中的格式有点不对。在我的手机上，所以在我输入答案时看不到问题!