collectionView（_：didDeselectItemsAt :)从未被调用 [英] collectionView(_:didDeselectItemsAt:) is never called

问题描述

因为某些原因，我的 NSCollectionView （使用我写的自定义布局）调用其委托的 collectionView（_：didSelectItemsAt：）函数当我点击一个项目，但不是相同的代理的 collectionView（_：didDeselectItemsAt：）当我点击它。

这是我的基本设置：

  class MyCollectionViewContainer：NSViewController {
 fileprivate lazy var collectionView ：NSCollectionView = {
 let collectionView = NSCollectionView（）
 collectionView.delegate = self 
 collectionView.dataSource = self 
 
 collectionView.collectionViewLayout = self.customLayout 
 collectionView.isSelectable = true 
 collectionView.allowsEmptySelection = true 
 collectionView.allowsMultipleSelection = false 
}（）
} 
 
扩展MyCollectionViewContainer：NSCollectionViewDelegate {
 
 func collectionVie w（_ collectionView：NSCollectionView，didSelectItemsAt indexPaths：Set< IndexPath>）{
 
 print（Selected，indexPaths）
 
 //突变数据以反映该选择
 
 
 func collectionView（_ collectionView：NSCollectionView，didDeselectItemsAt indexPaths：Set< IndexPath>）{
 print（Deselected，indexPaths）
} 
} 
  

未选择从未打印...：/

解决方案

所以原来我的布局没有添加任何补充视图，类型为 NSCollectionElementKindInterItemGapIndicator ;显然，这是集合视图用于检测何时点击某个项目的视图。我的快速解决方案是在我的布局中添加一个巨大的，跨越整个集合视图，并使其Z索引低于所有其他项目和补充视图。

For some reason, my NSCollectionView (which uses a custom layout that I wrote) calls its delegate's collectionView(_:didSelectItemsAt:) function when I click an item, but not that same delegate's collectionView(_:didDeselectItemsAt:) when I click off it.

Here's my basic setup:

class MyCollectionViewContainer: NSViewController {
    fileprivate lazy var collectionView: NSCollectionView = {
        let collectionView = NSCollectionView()
        collectionView.delegate = self
        collectionView.dataSource = self

        collectionView.collectionViewLayout = self.customLayout
        collectionView.isSelectable = true
        collectionView.allowsEmptySelection = true
        collectionView.allowsMultipleSelection = false
    }()
}

extension MyCollectionViewContainer: NSCollectionViewDelegate {

    func collectionView(_ collectionView: NSCollectionView, didSelectItemsAt indexPaths: Set<IndexPath>) {

        print("Selected", indexPaths)

        // Mutate data to reflect that selection
    }

    func collectionView(_ collectionView: NSCollectionView, didDeselectItemsAt indexPaths: Set<IndexPath>) {
        print("Deselected", indexPaths)
    }
}

"Deselected" is never printed... :/

解决方案

So it turns out my layout wasn't adding any supplementary views of type NSCollectionElementKindInterItemGapIndicator; apparently this is the view that the collection view uses to detect when you click off an item. My quick solution was to add one huge one to my layout that spans the entire collection view, and make its Z index below that of all other items and supplementary views.

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