UICollectionView:有没有办法只重新加载补充视图? [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 我都有一些按钮.在 dataSource 方法 collectionView:viewForSupplementaryElementOfKind:atIndexPath: 我使用 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部分(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，但我不想重新加载每个部分的所有项目.

我试过了:

• 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，但这种方法会增加我的 supplementaryViews.
• collectionView.subviews 中的快速 for 并仅获取 supplementaryView 并调用 layoutIfNeeded 方法，但它不会重新加载，只是布局正在重新加载.
• 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(delegate) 来插入和删除部分.

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

谁能帮我解决这个问题?有没有办法只重新加载 supplementaryView?这种情况还有其他方法吗?

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，您可以使用 -invalidateLayoutWithContext:.

To reload supplementary views you can use -invalidateLayoutWithContext:.

请参阅 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).

这篇关于UICollectionView:有没有办法只重新加载补充视图?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！