NSOutlineView doesn't Collapse Item

Question

I have a NSOutlineView, and clicking on a row will expand/collapse the item if it's expandable.

    if ([self.outlineView isItemExpanded:item]) {
        NSLog("Will collapse item : %@", item);
        [[self.outlineView animator] collapseItem:item];
    }
    else {
        [[self.outlineView animator] expandItem:item];
    }

Expanding the item works as expected, however collapsing the item is not working. I did get the log before executing collapseItem:, and the item is correct. The delegate method - (BOOL)outlineView:(NSOutlineView *)outlineView shouldCollapseItem:(id)item was not called too.

Have been on this problem for hours. Any ideas what causes this?

Answer 1

I figured it out. Seems the item is collapsable only when - (BOOL)outlineView:(NSOutlineView *)outlineView shouldShowOutlineCellForItem:(id)item returns YES for that item. Otherwise, you can only expand the item.

Answer 2

In my case, my item is struct so those function didn't work. Then I need to change to class, and it worked. Because when I use this code "let item = outlineView.item(atRow: selectedIndex)" in struct it will copy value and create new object. So outlineView can't recognize the item => it won't work

    let selectedIndex = outlineView.selectedRow
    if let item = outlineView.item(atRow: selectedIndex) {
        if outlineView.isItemExpanded(item) {
            outlineView.collapseItem(item, collapseChildren: true)
        }else {
            outlineView.expandItem(item, expandChildren: true)
        }
    }

Answer 3

This works really fine for me

id item = [sender itemAtRow:[sender clickedRow]];
if ([self outlineView:sender isItemExpandable:item]) {
    if ([sender isItemExpanded:item])
        [sender collapseItem:item];
    else
        [sender expandItem:item];
}

Answer 4

Item of NSOutlineView will collapse or not depends upon below method, return true if you want to collapse otherwise false.

func outlineView(_ outlineView: NSOutlineView, shouldShowOutlineCellForItem item: Any) -> Bool

I tried to make same a demo like MAC system preference -> keyboard -> Shortcuts

func outlineView(_ outlineView: NSOutlineView, shouldShowOutlineCellForItem item: Any) -> Bool {

    let isExpanded = outlineView.isItemExpanded(item)

    if isExpanded {

        return true

    } else {

        return false
    }
}

func outlineView(_ outlineView: NSOutlineView, viewFor tableColumn: NSTableColumn?, item: Any) -> NSView? {

    let view = outlineView.makeView(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "OutlineTableCell"), owner: self) as! OutlineTableCell

    view.setOutlineTableCellLaytout(forNode: (item as? SectionTreeNode)!)

    view.disclosure.action = nil

    view.disclosure.action = #selector(didDisclosureClicked(_:))

    view.selectedItem = item as? SectionTreeNode

    return view

}

@objc func didDisclosureClicked(_ sender: NSButton) {

    let view = sender.superview?.superview as? OutlineTableCell

    let isExpand = outlineView.isItemExpanded(view?.selectedItem)

    isExpand ? outlineView.collapseItem(view?.selectedItem, collapseChildren: true) : outlineView.expandItem(view?.selectedItem, expandChildren: true)

}

My output is below image: