swift - CollectionView 单元格 困惑

Question

我正忙于开发带有音板的语音应用程序，当您点击 CollectionView Cell 时，iPhone 就会说出文本。我的应用程序有一个小错误，我不知道原因是什么。

我已经构建了一个 CollectionView，其中图像作为背景 View 。它有效，但是当我转到其他 View (例如“绘画” View )时，我会返回，然后单元格会混淆。

谁能告诉我出了什么问题以及如何解决它？

谢谢!

这是我的代码:

 override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    managedObjectContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    loadData()

    let itemSize = UIScreen.main.bounds.width/2 - 5
    let itemHeight = itemSize / 2
    let layout = UICollectionViewFlowLayout()
    layout.sectionInset = UIEdgeInsets.init(top: 3, left: 3, bottom: 3, right: 3)
    layout.itemSize = CGSize(width: itemSize, height: itemHeight)

    layout.minimumInteritemSpacing = 3
    layout.minimumLineSpacing = 3

    soundboard.collectionViewLayout = layout

    navigationItem.rightBarButtonItem = editButtonItem

    if(traitCollection.forceTouchCapability == .available){
        registerForPreviewing(with: self as UIViewControllerPreviewingDelegate, sourceView: collectionView)
    }
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)

    loadData()
}

func loadData() {
    let soundRequest:NSFetchRequest<Soundboard> = Soundboard.fetchRequest()

    do {
        soundBoardData = try managedObjectContext.fetch(soundRequest)
        self.soundboard.reloadData()
    } catch {
        print("Error")
    }
}


// MARK: - Collection View
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return soundBoardData.count
}

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> soundboardCellVC {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! soundboardCellVC

    let soundItem = soundBoardData[indexPath.row]


    if let getCellPhoto = soundItem.photo as Data? {

        cell.title.text = "";

        let cellPhoto = UIImage(data: getCellPhoto)


        let cellPhotoFrame = UIImageView(image:cellPhoto)


        cellPhotoFrame.frame = CGRect(x: 0, y: 0, width: cell.frame.width, height: cell.frame.height)
        cellPhotoFrame.contentMode = UIView.ContentMode.scaleAspectFill

        cell.backgroundView = UIView()
        cell.backgroundView!.addSubview(cellPhotoFrame)
    }
    else
    {
        cell.title.text = soundItem.title;

        cell.backgroundColor = UIColor(red: CGFloat(soundItem.colorRed), green: CGFloat(soundItem.colorGreen), blue: CGFloat(soundItem.colorBlue), alpha: 1)

        let fontAwesomeIcon = FAType(rawValue: Helper.FANames.index(of: soundItem.icon!)!)

        cell.icon.setFAIconWithName(icon: fontAwesomeIcon!, textColor: UIColor.white)
    }

    cell.layer.cornerRadius = 10
    cell.layer.masksToBounds = true

    cell.delegate = self as SoundboardCellDelegate

    return cell
}

Answer 1

使用单元格时的一个好习惯是清除单元格重用时您不希望保留的所有属性。

https://developer.apple.com/documentation/uikit/uicollectionreusableview/1620141-prepareforreuse

例如，在您的单元格类中，您可以执行以下操作:

override func prepareForReuse() {
    super.prepareForReuse()
    self.title.text = nil
}

这使您的 cellForItem 方法更加清晰，并且您可以确定在重用它之前会执行上述操作。