UICollectionView:是否有一种方法可以仅重新加载补充视图? [英] UICollectionView: Is there a way to reload only the supplementary views?

问题描述

每个部分都有一个带有 supplementaryView 的uicollectionview. 在每个 supplementaryView 中，我都有一些按钮. 在数据源方法 collectionView:viewForSupplementaryElementOfKind:atIndexPath:中，我正在使用 indexPath.section 设置按钮标签.当按下按钮时，我做了一些委托方法，并将section(button.tag)作为参数发送.

I have an uicollectionview with supplementaryView for each section. In each supplementaryView I have some buttons. In dataSource method collectionView:viewForSupplementaryElementOfKind:atIndexPath: I'm setting the buttons tags with the indexPath.section. I made some delegate methods when a button is pressed and send the section(button.tag) as parameter.

一切正常，但是问题来了:

Everything works fine, but here comes the problem:

• 当我插入或删除一个部分时，它必须更新按钮标签，但是我不想重新加载每个部分中的所有项目.

我尝试过:

• 使用dataSource方法 collectionView:viewForSupplementaryElementOfKind:atIndexPath:获取补充视图，并为每个 supplementaryView 调用 layoutIfNeeded 方法，这样 supplementaryViews 正在重新加载，但是这种方法使我的 supplementaryViews 倍增.
在 collectionView.subviews 中
• 一个快速的 for ，仅获取 supplementaryView 并调用 layoutIfNeeded 方法，但是不重新加载，仅重新加载布局.
• reloadSections:方法，但这会重新加载
部分中的所有项目

• to get the supplementaryViews with the dataSource method collectionView:viewForSupplementaryElementOfKind:atIndexPath: and call layoutIfNeeded method for each supplementaryView, in this way the supplementaryViews are reloading, but this approach multiply my supplementaryViews.
• a fast for in collectionView.subviews and get just the supplementaryView and call layoutIfNeeded method, but it doesn't reload, just the layout is reloading.
• reloadSections: method, but this reload all items from the section

哦.我使用 NSFetchedResultsController (委托)插入和删除节.

Ohh.. And I use NSFetchedResultsController(delegate) for inserting and deleting sections.

有人可以帮我吗?有没有办法只重新加载 supplementaryView ?在这种情况下还有其他方法吗?

Can anyone help me with this? Is there a way to reload only the supplementaryView? Is there other approach for this scenario?

谢谢！

推荐答案

要重新加载补充视图，可以使用-invalidateLayoutWithContext:.

To reload supplementary views you can use -invalidateLayoutWithContext:.

请参见UICollectionViewLayoutInvalidationContext和方法-invalidateSupplementaryElementsOfKind:atIndexPaths:的文档(自iOS 8起可用).

See documentation for UICollectionViewLayoutInvalidationContext and method -invalidateSupplementaryElementsOfKind:atIndexPaths: (available since iOS 8).

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