如何使补充视图在 UICollectionView 中浮动，就像部分标题在 UITableView 普通样式中一样 [英] How to make Supplementary View float in UICollectionView as Section Headers do in UITableView plain style

问题描述

我正在努力使用 UICollectionView 实现浮动节标题"效果.在 UITableView 中已经足够简单的事情(UITableViewStylePlain 的默认行为)在 UICollectionView 中似乎是不可能的，除非付出大量的努力.我错过了显而易见的事情吗?

I'm struggling to achieve a "floating section header" effect with UICollectionView. Something that's been easy enough in UITableView (default behavior for UITableViewStylePlain) seems impossible in UICollectionView without lots of hard work. Am I missing the obvious?

Apple 没有提供有关如何实现此目的的文档.似乎必须继承 UICollectionViewLayout 并实现自定义布局才能达到此效果.这需要相当多的工作，实现以下方法:

Apple provides no documentation on how to achieve this. It seems that one has to subclass UICollectionViewLayout and implement a custom layout just to achieve this effect. This entails quite a bit of work, implementing the following methods:

重写方法

每个布局对象都应该实现以下方法:

Every layout object should implement the following methods:

collectionViewContentSize
layoutAttributesForElementsInRect:
layoutAttributesForItemAtIndexPath:
layoutAttributesForSupplementaryViewOfKind:atIndexPath: (if your layout supports supplementary views)
layoutAttributesForDecorationViewOfKind:atIndexPath: (if your layout supports decoration views)
shouldInvalidateLayoutForBoundsChange:

但是，我不清楚如何使补充视图漂浮在单元格上方并粘"到视图顶部，直到到达下一部分.布局属性中是否有此标志?

However its not clear to me how to make the supplementary view float above the cells and "stick" to the top of the view until the next section is reached. Is there a flag for this in the layout attributes?

我会使用 UITableView 但我需要创建一个相当复杂的集合层次结构，这可以通过集合视图轻松实现.

I would have used UITableView but I need to create a rather complex hierarchy of collections which is easily achieved with a collection view.

任何指导或示例代码将不胜感激！

Any guidance or sample code would be greatly appreciated!

推荐答案

在 iOS9 中，Apple 好心在 UICollectionViewFlowLayout 称为 sectionHeadersPinToVisibleBounds.

In iOS9, Apple was kind enough to add a simple property in UICollectionViewFlowLayout called sectionHeadersPinToVisibleBounds.

有了这个，你可以让表头像在表格视图中那样浮动.

With this, you can make the headers float like that in table views.

let layout = UICollectionViewFlowLayout()
layout.sectionHeadersPinToVisibleBounds = true
layout.minimumInteritemSpacing = 1
layout.minimumLineSpacing = 1
super.init(collectionViewLayout: layout)

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