通过单击取消选择NSCollectionViewItem

Question

如何通过再次单击NSCollectionViewItem来取消选择它？

这是我用来选择和取消选择的代码：

func collectionView(collectionView: NSCollectionView, didSelectItemsAtIndexPaths indexPaths: Set<NSIndexPath>) {
        print("selected")
        guard let indexPath = indexPaths.first else {return}
        print("selected 2")
        guard let item = collectionView.itemAtIndexPath(indexPath) else {return}
        print("selected 3")
        (item as! CollectionViewItem).setHighlight(true)
    }

    func collectionView(collectionView: NSCollectionView, didDeselectItemsAtIndexPaths indexPaths: Set<NSIndexPath>) {
        print("deselect")
        guard let indexPath = indexPaths.first else {return}
        print("deselect 2")
        guard let item = collectionView.itemAtIndexPath(indexPath) else {return}
        print("deselect 3")
        (item as! CollectionViewItem).setHighlight(false)
    }

/////////////////////

    class CollectionViewItem: NSCollectionViewItem {


        func setHighlight(selected: Bool) {

            print("high")
            view.layer?.borderWidth = selected ? 5.0 : 0.0
            view.layer?.backgroundColor = selected ? NSColor.redColor().CGColor : NSColor(calibratedRed: 204.0/255, green: 207.0/255, blue: 1, alpha: 1).CGColor
        }
    }

此代码在单击另一项时取消选择，但不在同一项被单击时取消选择。当相同的项目被点击时，我想删除。

Answer 1

您可以通过观察项目的选中状态来实现这一点，当项目处于选中状态时，在项目的视图上安装NSClickGestureRecognizer，在取消选中项目时将其卸载。

将以下代码放在您的NSCollectionViewItem子类中的某个位置：

- (void)onClick:(NSGestureRecognizer *)sender {
    if (self.selected) {
        //here you can deselect this specific item, this just deselects all
        [self.collectionView deselectAll:nil];
    }
}

- (void)setSelected:(BOOL)selected {
    [super setSelected:selected];
    if (selected) {
        [self installGestureRecognizer];
    }
    else {
        [self uninstallGestureRecognizer];
    }
}

- (void)installGestureRecognizer {
    [self uninstallGestureRecognizer];

    self.clickGestureRecognizer = [[NSClickGestureRecognizer alloc] initWithTarget:self
                                                                            action:@selector(onClick:)];
    [self.view addGestureRecognizer:self.clickGestureRecognizer];
}

- (void)uninstallGestureRecognizer {
    [self.view removeGestureRecognizer:self.clickGestureRecognizer];
    self.clickGestureRecognizer = nil;
}

Answer 2

一个简单的技巧是使用CMD -鼠标左键单击。虽然这不能完全解决我的问题，但总比什么都没有好。

Answer 3

感谢Marko Hlebar的answer。

在此基础上，实现了点击项目切换选择的功能。

class MyItem: NSCollectionViewItem {
    override var isSelected: Bool {
        didSet {
            self.view.layer?.backgroundColor = (isSelected ? NSColor.blue : NSColor.gray).cgColor
            // If the selection causes the size to change, re-layout.
            self.collectionView?.collectionViewLayout?.invalidateLayout()
        }
    }

    override func viewDidLoad() {
        self.view.wantsLayer = true
        self.view.addGestureRecognizer(NSClickGestureRecognizer(target: self, action: #selector(onClick(sender:))))
    }

    @objc private func onClick(sender: NSGestureRecognizer) {
        guard let indexPath = self.collectionView?.indexPath(for: self) else { return }
        if self.isSelected {
            self.collectionView?.deselectItems(at: [indexPath])
        } else {
            self.collectionView?.selectItems(at: [indexPath], scrollPosition: [])
        }
    }
}