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macoscocoaappkitnscollectionview

Select Item in NSCollectionView on mouseDown, not mouseUp?

I'd like to make it so my NSCollectionView's selection behavior matches the icon-view in Finder. Finder will select and highlight elements when the mouse button is clicked down, but NSCollectionView's built in behavior appears to use mouse up to trigger a selection.

Is there a way to make NSCollectionView act like Finder in this regard?

Solution

  • Per pfandtrade's comment above, it looks like the highlight state of an NSCollectionViewItem will be changed before that item is selected.

    mouseDown = NSCollectionViewItem's highlightState is set to forSelection

    mouseUp = NSCOllectionViewItem's highlightState is set to none, but isSelected property is then set to true.

    I added the following to my NSCollectionViewItem subclass:

    override var highlightState: NSCollectionViewItemHighlightState{
    didSet{
        if self.highlightState == .forSelection{
            self.showSelectedHighlight() //my stylization function
        }
    }
}