Question

我的CellClass内部有一个协议，该协议检测功能'editCommentInFeed'。我已经在单元格中创建了一个“ editButton”，并定义了带有“ editCommentField”的处理程序，该处理程序每调用一次Delegate函数并给出2个参数。这2个参数很重要，我需要从单元格获取此信息以检测将来将要提供的操作。

例如，当我在单元格内部按下按钮时，我曾尝试打印一些东西。但是，即使该语句也无法执行。


//This is the Cell Class

protocol CommentFeedProtocol {
    func editCommentInFeed(cell: CommentCell, comment: Comment)
}

class CommentCell: BaseCell {

      var delegate: CommentFeedProtocol?

      let editButton: UIButton = {

        let editbttn = UIButton(type: UIButton.ButtonType.system)
        editbttn.setImage(UIImage(named: "editButton"), for: UIControl.State.normal)
        editbttn.addTarget(self, action: #selector(editCommentField), for: UIControl.Event.touchUpInside)

        return editbttn
    }()


    override func setUpCell() {
        super.setUpCell()

        backgroundColor = UIColor.white


        setUpCommentCell()

    }

    fileprivate func setUpCommentCell(){

        addSubview(profileImageView)
        addSubview(editButton)
        addSubview(commentTextView)
        addSubview(seperator)

        profileImageView.anchor(top: topAnchor, left: leftAnchor, bottom: nil, right: nil, paddingTop: 8, paddingLeft: 8, paddingBottom: 0, paddingRight: 0, width: 40, height: 40)
        profileImageView.layer.cornerRadius = 40/2

        editButton.anchor(top: topAnchor, left: nil, bottom: bottomAnchor, right: rightAnchor, paddingTop: 5, paddingLeft: 0, paddingBottom: 5, paddingRight: 10, width: 45, height: 0)

        commentTextView.anchor(top: topAnchor, left: profileImageView.rightAnchor, bottom: bottomAnchor, right: editButton.leftAnchor, paddingTop: 4, paddingLeft: 4, paddingBottom: 4, paddingRight: 4, width: 0, height: 0)

        seperator.anchor(top: bottomAnchor, left: leftAnchor, bottom: nil, right: rightAnchor, paddingTop: 5, paddingLeft: 20, paddingBottom: 0, paddingRight: 20, width: 0, height: 1.5)


    }


    /*Objecthandler*/

    @objc func editCommentField(){
        guard let comment = comment else { return}
        delegate?.editCommentInFeed(cell: self, comment: comment)
    }


// This is the CollectionViewController
// As you can see I am also add the Protocol to the class 

class CommentsController: UICollectionViewController, UICollectionViewDelegateFlowLayout, CommentFeedProtocol {

override func viewDidLoad() {
        super.viewDidLoad()

        navigationItem.title = "Kommentare"

        postButton.imageView?.alpha = 0.5
        postButton.isEnabled = false


        collectionView.keyboardDismissMode = .interactive
        collectionView.register(CommentCell.self, forCellWithReuseIdentifier: commentCell)
        collectionView.alwaysBounceVertical = true

        self.collectionView.backgroundColor = UIColor.white

        fetchComments()

    }


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


        cell.comment = comments[indexPath.item]
        cell.delegate = self

        return cell
    }

// Here is the Delegate Function

    func editCommentInFeed(cell: CommentCell, comment: Comment) {
        print("Button was Pressed")
    }

您可以在示例中看到我正在将协议添加到类中，并且还在类中调用了该函数。我没有收到错误消息。单击按钮时，该按钮仅会悬停在上方，但不执行任何操作？！

Answer 1

似乎委托未设置为您的ViewController。在cellForItemAt函数中，您需要设置cell.delegate = self。因此，当您的单元格调用delegate.editCommentInFeed时，它实际上会调用viewController的editCommentInFeed实现的函数。

Answer 2

您尚未在cellForItemAt中设置委托：

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: commentCell, for: indexPath) as! CommentCell
    cell.comment = comments[indexPath.item]
    cell.delegate = self. // You forgot to add this line

    return cell
}

您可以在此处了解更多信息：

https://developer.apple.com/library/archive/documentation/General/Conceptual/CocoaEncyclopedia/DelegatesandDataSources/DelegatesandDataSources.html

您还可以搜索有关此内容的出色教程。

UICollectionViewCell协议不起作用

2 个答案: