尝试为 UICollectionView Swift 添加 header 时出错

Question

我在尝试将 header 添加到我的 collection 视图时遇到问题。这是代码的相关部分：

collectionView?.register(ProfileHeaderView.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: Identifier.header)

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize{
    return CGSize(width: view.frame.width, height: 262.5)
}

override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
    if member == nil {
        return UICollectionReusableView()
    }
    switch kind {
    case UICollectionElementKindSectionHeader:
        let profileHeaderView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: Identifier.header, for: indexPath) as! ProfileHeaderView
        if indexPath.section == Section.header {
            profileHeaderView.config(...)
            return profileHeaderView
        } else {

            let reusabelView = UICollectionReusableView()
            let seperatorLine = UIView.seperatorLine()

            reusabelView.addSubview(seperatorLine)
            seperatorLine.bottomAnchor.constraint(equalTo: reusabelView.bottomAnchor).isActive = true
            seperatorLine.leftAnchor.constraint(equalTo: reusabelView.leftAnchor).isActive = true
            seperatorLine.centerXAnchor.constraint(equalTo: reusabelView.centerXAnchor).isActive = true

            reusabelView.backgroundColor = Color.white
            return reusabelView
        }
    default:
        return UICollectionReusableView()
    }
}

ProfileHeaderView是UICollectionReusableView的子类。在运行这段代码并试图查看它的样子之后，我得到了这个错误：

the view returned from -collectionView:viewForSupplementaryElementOfKind:atIndexPath (UICollectionElementKindSectionHeader, {length = 2, path = 0 - 0}) was not retrieved by calling -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath: or is nil (>) (null)

Answer 1

我觉得你的条件有问题。

您收到的消息告诉您您没有将补充视图从 collectionView 中取出。所以问题在于您 func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView returns 创建（初始化）视图的部分。

您的集合视图中的所有视图都必须从中取出。您可以在 documentation 中阅读更多内容。

尝试为 UICollectionView Swift 添加 header 时出错

Error trying to add header for UICollectionView Swift

uicollectionview

swift

swift3