UICollectionView:在标题和项之间添加间距

Question

我想在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

您基本上是在为集合视图部分添加上边距,因为您将为该部分设置顶部插入.要在代码中执行此操作,请执行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)
}

如果你不想实现insetForSectionAtIndex,你也可以用适当的方法做这样的事情,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Flow Layout时有效.

Answer 2

您可以做的一种方法是使用以下方法增加标头容器的高度

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)
}