UICollectionView：在标题和项目之间添加间距

Question

我想在我的标题和实际项目之间添加一些间距，目前看起来像这样：

func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
    // Create header
    switch kind{
        case UICollectionElementKindSectionHeader:
            let headerView = iconCollectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: "customIconHeaderView", forIndexPath: indexPath) as! CustonIconHeaderView
            headerView.setUp() //add whatever into the view
            return headerView
        default:
            assert(false, "Unexpected element kind")
    }

}

Answer 1

您基本上是在谈论为集合视图部分添加上边距，因为您将为该部分设置 top inset。要在代码中实现，请实现 insetForSectionAtIndex:

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {
    return UIEdgeInsets(top: 10.0, left: 1.0, bottom: 1.0, right: 1.0)
}

如果您不想实现insetForSectionAtIndex，您也可以在适当的方法中执行类似的操作，例如viewDidLoad:

let layout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
layout.sectionInset = UIEdgeInsets(top: 10.0, left: 1.0, bottom: 1.0, right: 1.0)

在 Interface Builder 中，选择集合视图并更改 Section Insets -> Top 的值，如下图所示：

注意：这仅在您使用流式布局时有效。

Answer 2

您可以做的一种方法是使用增加标题容器的高度

collectionView(_:layout:referenceSizeForHeaderInSection:)

例子：

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    return CGSize(width: 0, height: yourHeaderContentHeight + yourHeaderMarginToCell)
}

编辑：

func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
    let headerView = collectionView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "YourID", forIndexPath: indexPath)

    let yourCustomView = UIView(frame: CGRect(x: 0, y: 0, width: yourHeaderWidth, height: yourHeaderHeight))

    headerView.addSubview(yourCustomView)

    return headerView
}

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    return CGSize(width: yourHeaderWidth, height: yourHeaderHeight + yourHeaderMargin)
}